Skin/Hair

Question 1

A 12-year-old white male who lives in a household with several cats presents with axillary lymphadenopathy. Which one of the following is the best initial test for establishing a diagnosis of cat-scratch disease? (check one)
Lymph node biopsy
Blood cultures
IgG testing for Bartonella henselae
IgG testing for nontuberculous Mycobacterium species

Answer 1

IgG testing for Bartonella Henselae

Bartonella henselae is the organism that causes cat-scratch disease. IgG titers over 1:256 strongly suggest active or recent infection. IgM elevation suggests acute disease but production of IgM is brief. Lymph node biopsy is reserved for cases where node swelling fails to resolve or the diagnosis is uncertain. The organism is difficult to culture and cultures are not recommended. Nontuberculous mycobacteria do not cause cat-scratch disease (SOR C).

Question 2

A 20-year-old African-American female asks if you can help eradicate an unsightly hypertrophic growth of skin that has developed in an area where she had a mole removed. She reports that this tissue has grown to become at least three times larger than the original lesion and that it is darkly pigmented, firm, and pruritic. On examination you note a firm, smooth, shiny, raised 1×4-cm plaque on the patient’s chest that is darker than the surrounding skin.

Which one of the following is first-line therapy for this lesion? (check one)
Silicone gel sheeting
Topical imiquimod (Aldara)
Intralesional corticosteroid injection
Surgical excision
Laser destruction

Answer 2

Intralesional corticosteroid injection

The patient’s history and physical findings are all consistent with a keloid, which is a benign overgrowth of scar tissue at sites of trauma to the skin, such as acne, burns, surgery, ear piercing, tattoos, and infections. Common locations include the earlobes, jawline, nape of the neck, scalp, chest, and back. Lesions are sometimes asymptomatic, but often are associated with hypersensitivity, pain, and pruritus. The incidence is higher in Blacks, Hispanics, and Asians. Intralesional corticosteroid injections are first-line therapy. Silicone gel sheeting, topical imiquimod, and intralesional fluorouracil can be used when first-line therapy fails, but these methods are more often associated with recurrence. Laser therapy and surgical excision are associated with a high rate of recurrence when used as monotherapy.

Question 3

A 20-year-old college student who has been working in the woods on a forestry project presents with a 3-to 4-day history of a severely pruritic rash on his arms, hands, and face. There is erythema with multiple bullae and vesicles, some of which are in a streaked linear distribution on the arms. There are patches of erythema on his face with some vesicles. The itching is intense and he sleeps fitfully.

In addition to cool compresses and antihistamines for the itching, which one of the following is the best treatment option for this patient? (check one)
Triamcinolone, 20 mg intramuscularly as a single dose
A 6-day oral methylprednisolone (Medrol) dose pack, starting at 24 mg
A 7- to 10-day course of topical halobetasol propionate (Ultravate), 0.05% ointment
A 7-to 10-day course of topical mupirocin (Bactroban) 2%, after decompression of vesicles and bullae
A 10- to 14-day tapering course of oral prednisone, starting at 60 mg

Answer 3

A 10- to 14-day tapering course of oral prednisone, starting at 60 mg

Poison ivy dermatitis is caused by urushiol, a resin found in poison ivy, poison oak, and poison sumac plants. Direct contact with the leaves or vines will result in an acute dermatitis manifested initially by erythema, and later in more severe cases by vesicles and bullae. This is a type IV T cell–mediated allergic reaction, so it typically takes at least 12 hours and often 2–3 days before the reaction is fully manifested. Depending on the degree of contact (i.e., the amount of resin on the skin), the rash often progresses over a couple of days, giving the impression that it is spreading. Also, delayed contact with resin from contaminated clothing, gloves, or pets may result in new lesions appearing over several days. Brushing against the leaves of the plant causes the linear streaking pattern characteristic of poison ivy dermatitis. It has been demonstrated that the resin can be inactivated with any type of soap, thereby preventing the reaction, but the sooner the better. Approximately 50% of the resin can be removed by soap and water within 10 minutes of contact, but after 30 minutes only about 10% can still be removed.

Therapy depends on the severity of the reaction. Group I–V topical corticosteroids are effective for limited eruptions (less than 3%–5% body surface area) but are ineffective in areas with vesicles or bullae. Group I–II fluorinated agents are at the strongest end of the spectrum and are not recommended for use on the face or intertriginous areas. Short bursts of low-potency oral corticosteroids such as a methylprednisolone dose pack have a high rate of relapse as the taper finishes, so the expert consensus is to use a higher dosage tapered over a longer period, generally 10–14 days, in order to prevent a relapse. Most experts recommend oral corticosteroids over intramuscular corticosteroid suspensions, which may not provide high enough concentrations in the skin (SOR C). However, 40–80 mg of intramuscular triamcinolone (or an equivalent) is an alternative to oral treatment, especially if adherence is an issue. Pruritus can be treated

Question 4

A 38-year-old female presents to the emergency department with an acute onset of fever, chills, and rapidly progressive right lower extremity redness. She reports being in her usual state of health until a few hours ago when she developed shaking chills and noted a fever of 103.0°F (39.4°C).

Shortly after she arrives she complains of right lower extremity pain and a bright red skin discoloration from her ankle to her right knee. She is also noted to have a heart rate of 123 beats/min and a WBC count of 22,000/mm3 (N 4300–10,800). Her past medical history is significant for congenital arthritis, a recent bilateral hip replacement, and recurrent lower extremity cellulitis.

You admit the patient to the hospital. When selecting an empiric treatment for this patient, which one of the following organisms should you be most concerned about? (check one)
Candida albicans
Chlamydia trachomatis
Mycoplasma hominis
Group A Streptococcus
Trichophyton rubrum

Answer 4

Group A Streptococcus

This patient has rapidly progressive erythema and pain in her right lower extremity, along with fever, tachycardia, and leukocytosis. Group A Streptococcus (GAS) is a common monomicrobial cause of type II necrotizing skin infections, which are often referred to as necrotizing fasciitis and warrant immediate attention (SOR C). Type I infections are often polymicrobial due to combinations of staphylococci (especially Staphylococcus epidermidis in combination with p-hemolytic streptococci), enterococci, Enterobacteriaceae species (commonly Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, and Pseudomonas aeruginosa), streptococci, Bacteroides/Prevotella species, anaerobic gram-positive cocci, and Clostridium species.

For this patient with a suspected necrotizing skin infection, aggressive treatment with a broad-spectrum empiric antibiotic is recommended along with hemodynamic support and consideration of surgical exploration and debridement of necrotic tissue (SOR C). Empiric antibiotic treatment of a potential necrotizing infection should consist of broad-spectrum antimicrobial therapy with activity against gram-positive, gram-negative, and anaerobic organisms; special consideration should be given to group A Streptococcus, Clostridium species, and methicillin-resistant Staphylococcus aureus (MRSA).

Question 5

A 30-year-old male is treated with topical medications for his papulopustular rosacea with only partial improvement. The preferred antibiotic is (check one)
amoxicillin
cephalexin (Keflex)
doxycycline
erythromycin
trimethoprim/sulfamethoxazole (Bactrim)

Answer 5

doxycycline

Tetracycline and its derivatives have historically been used for the treatment of papulopustular rosacea and there is data to support their use. A modified-release doxycycline is FDA-approved for this indication. Amoxicillin, cephalexin, erythromycin, and trimethoprim/sulfamethoxazole lack evidence to support their use in the treatment of papulopustular rosacea.

Question 6

A 24-year-old male who just moved to town for a new job presents to your office with a 2-week history of a rash. His previous medical records are not available. The physical examination reveals pink, scaling papules and plaques on the trunk and proximal aspect of the arms and legs. You suspect pityriasis rosea.

To complete the diagnostic evaluation you should order
(check one)
a fungal culture
heterophile antibody testing
a platelet count
a rapid plasma reagin (RPR) test
a TSH level

Answer 6

a rapid plasma reagin (RPR) test

The differential diagnosis of multiple small scaling plaques includes drug eruptions, secondary syphilis, guttate psoriasis, and erythema migrans. If the diagnosis cannot be made conclusively by clinical examination, a test for syphilis should be ordered. The rash of secondary syphilis may be indistinguishable from pityriasis rosea on initial examination, particularly when no herald patch is noted. The rashes associated with hyperthyroidism, infectious mononucleosis, idiopathic thrombocytopenic purpura, and fungal infections are not in the differential diagnosis for this patient.

Question 7

A 29-year-old female presents with a 1-week history of a rash on her legs. A full review of systems is significant only for regular borderline-heavy periods that lasted for 7 days during her last two menstrual cycles. She has not had any recent illness or hospitalization, and takes no medications. Her examination shows nonblanching purple macules on her upper legs.

A comprehensive metabolic panel reveals normal renal function and liver enzyme tests, and a urine pregnancy test is negative. A CBC reveals a platelet count of 27,000/mm3 (N 150,000–400,000) but is otherwise normal.

Which one of the following is the most likely cause of the rash? (check one)
Acute leukemia
Congenital thrombocytopenia
Immune thrombocytopenic purpura
Thrombotic thrombocytopenic purpura
Henoch-Schönlein purpura

Answer 7

Immune thrombocytopenic purpura

The rash described in this patient with significant thrombocytopenia is consistent with purpura. Purpura from vasculitic causes such as meningococcal infection, disseminated intravascular coagulation, or Henoch-Schönlein purpura (also known as IgA nephropathy) is typically palpable rather than macular as in this case. Immune thrombocytopenic purpura is a relatively common cause of isolated thrombocytopenia. The lack of systemic symptoms or other abnormal laboratory findings make acute lymphoproliferative disorders such as leukemia unlikely. Likewise anemia, neurologic changes, fever, and renal failure are seen with thrombotic thrombocytopenic purpura. The acute onset of purpura and heavy periods makes congenital thrombocytopenia unlikely.

Question 8

A 4-year-old female is treated at a local urgent care center with amoxicillin for acute pharyngitis. Several days after starting treatment her initial symptoms resolve. When she is 8 days into the 10-day course of her antibiotic treatment she returns to your office because she has developed a diffuse erythematous maculopapular rash starting on her torso and extending to her proximal extremities.

Which one of the following is the best course of action at this time? (check one)
Continue the amoxicillin and begin prednisone and diphenhydramine (Benadryl)
Continue the amoxicillin and change the diagnosis to scarlet fever
Discontinue the amoxicillin and change the diagnosis to viral exanthem
Discontinue the amoxicillin and note amoxicillin as a potential allergy in her record

Answer 8

Discontinue the amoxicillin and note amoxicillin as a potential allergy in her record

The cause of this patient’s rash is difficult to determine. There are many infections that could result in a cutaneous reaction similar to what she is experiencing. Scarlet fever is caused by a systemic reaction to Streptococcus. In this case, however, the patient is already taking an antibiotic for streptococcal disease so the emergence of new symptoms over a week after starting therapy is highly unlikely. A viral exanthem could also cause a skin rash similar to the one described here. Unfortunately, differentiating between a drug-induced rash and a viral exanthem is not clinically possible. If this differentiation is necessary, the patient should undergo a skin biopsy and allergy testing to determine the offending agent. However, since this approach is impractical in the ambulatory setting, it is most straightforward to discontinue the agent she is on and list it as a potential allergy. An alternative antibiotic such as erythromycin could be used to complete the course of treatment at the discretion of the physician.

Question 9

A 23-year-old male presents with a skin rash on his chest and back. An examination reveals widespread, slightly pink macules on his chest and back. A KOH preparation is shown below.

Which one of the following would be the most appropriate treatment? (check one)
Topical nystatin cream
Topical selenium sulfide
Topical triamcinolone cream
Oral fluconazole (Diflucan)
Oral nystatin

Answer 9

Topical selenium sulfide

This image shows typical hyphae of pityriasis versicolor, a superficial infection caused by yeasts in the genus Malassezia. Of the listed therapies, topical selenium sulfide would be the most appropriate first-line treatment. Topical antifungals such as terbinafine and miconazole are other first-line options. Oral fluconazole can be used, but oral therapy is usually reserved for when topical treatment is impractical or unsuccessful. Topical nystatin cream and oral nystatin are ineffective, and topical corticosteroids such as triamcinolone may temporarily suppress symptoms while exacerbating the infection.

Question 10

An 18-month-old female with atopic dermatitis is brought to your office. She has recently had a flare-up of her condition that has been slow to resolve, and the mother says the child scratches “constantly” despite daily use of emollients.

Which one of the following would be the best treatment? (check one)
A topical mild-potency corticosteroid
Topical pimecrolimus (Elidel)
Oral diphenhydramine (Benadryl)
Oral cetirizine (Zyrtec)
Probiotics

Answer 10

A topical mild-potency corticosteroid

Topical corticosteroids are the first-line treatment for atopic dermatitis flare-ups. Topical calcineuron inhibitors such as pimecrolimus are a second-line therapy, but carry a warning of a possible link to lymphomas and skin malignancies and are not recommended for children under 2 years of age. Oral antihistamines are not effective for the pruritus associated with atopic dermatitis. Probiotic use is not supported by available evidence.

Question 11

Which one of the following tests should you obtain in a patient with lichen planus? (check one)
Antihistone antibodies
Hepatitis C antibody
HIV antibody
Sjögren syndrome–related antigen A (Ro) and Sjögren syndrome–related antigen B (La) antibodies

Answer 11

Hepatitis C antibody

Lichen planus is a disorder of unknown etiology affecting the skin, genitals, oral cavity, scalp, nails, and esophagus. Patients with lichen planus have a higher (up to sixfold) incidence of hepatitis C virus infection. Hence, screening for hepatitis C should be performed in patients with lichen planus even though the cause-and-effect relationship between hepatitis C and lichen planus is unknown.§Antihistone antibodies are present in patients with medication-induced lupus erythematosus. HIV antibody is used in screening for HIV infection. Sjögren syndrome–related antigen A (Ro) and Sjögren syndrome–related antigen B (La) antibodies are present in patients with Sjögren syndrome.

Question 12

A 12-year-old female is brought to your office by her mother for evaluation of a knee abrasion sustained earlier that day when she fell off her bike onto a gravel driveway. Her immunizations are up to date, including Tdap vaccination last year. A physical examination reveals an irregular, superficial abrasion measuring roughly 1×2 cm, containing dirt and stony debris.

Which one of the following infection prevention measures would be most appropriate in this situation? (check one)
Irrigation with tap water
Irrigation with 3% hydrogen peroxide
A topical antibiotic
An oral antibiotic
A tetanus booster

Answer 12

Irrigation with tap water

The most important aspect of infection prevention in treating a superficial wound is cleaning and irrigation. Studies have shown that irrigation with tap water provides similar outcomes compared to sterile saline (SOR B). Antiseptic solutions such as hydrogen peroxide are no more effective than tap water, can be caustic to wound tissue, and may delay healing (SOR C). Antibiotics should be used for treatment of wound infections; however, non-infected wounds do not routinely require antibiotic prophylaxis unless there is an increased risk of infection. Risk factors for wound infection include bite wounds, delayed presentation, retained foreign material, insufficient cleaning, puncture or crush wounds, open fractures, significant immunocompromise, and joint, cartilage, or tendon involvement. Patients with three or more doses of tetanus toxoid with the most recent vaccination within the past 5 years do not require a tetanus booster or tetanus immune globulin for prophylaxis, regardless of the type of wound.

Question 13

Which one of the following topical corticosteroids should be AVOIDED for long-term use on the face? (check one)
Clobetasol 0.05% lotion (Clobex)
Desonide 0.05% ointment (Desowen)
Hydrocortisone 1% lotion
Hydrocortisone 2.5% cream
Triamcinolone 0.025% cream

Answer 13

Clobetasol 0.05% lotion (Clobex)

Topical corticosteroids are extremely common agents prescribed by family physicians and it is important to understand the safe and appropriate use of these agents. Many common dermatologic conditions are best treated with mid- or low-potency corticosteroids, but some conditions will only improve with high-potency agents. High-potency agents should typically be avoided on the face and eyelids, and on infants. These agents should be used as sparingly as possible when indicated and tapered off (SOR B). Of the agents listed, clobetasol 0.05% lotion is a very high-potency corticosteroid and should be avoided for long-term use on the face. Desonide 0.05% ointment, hydrocortisone 1% lotion, hydrocortisone 2.5% cream, and triamcinolone 0.025% cream are low-potency corticosteroids.

Question 14

A 44-year-old male with papulopustular rosacea sees you for follow-up. You have been treating his condition with topical azelaic acid (Finacea), and although his condition is improved he is not satisfied with the results.
You suggest adding which one of the following oral medications? (check one)
Clarithromycin (Biaxin)
Clindamycin (Cleocin)
Doxycycline
Erythromycin
Metronidazole (Flagyl

Answer 14

Doxycycline

The only FDA-approved oral treatment for acne rosacea is doxycycline at a subantimicrobial dosage (40 mg daily). This does not contribute to antibiotic resistance, even when used over several months, and is better tolerated than higher dosages. Other antibiotics have limited and low-quality supporting evidence of efficacy and may lead to antibiotic resistance.

Question 15

A 52-year-old male has a skin lesion removed from his arm with appropriate sterile precautions. Which one of the following would be most appropriate to use on this surgical wound? (check one)
Petrolatum
Silver sulfadiazine (Silvadene) cream
Mupirocin (Bactroban) ointment
Polymyxin B/bacitracin ointment (Polysporin)
Triple-antibiotic (neomycin/polymyxin B/bacitracin) ointment

Answer 15

Petrolatum

The American Academy of Dermatology recommends against the routine use of topical antibiotics for clean surgical wounds, based on randomized, controlled trials. Topical antibiotics have not been shown to reduce the rate of infection in clean surgical wounds compared to the use of nonantibiotic ointment or no ointment. Studies have shown that white petrolatum ointment is as effective as antibiotic ointment in postprocedure care.
Topical antibiotics can aggravate open wounds, hindering the normal wound-healing process. In addition, there is a significant risk of developing contact dermatitis, as well as a potential for antibiotic resistance. Antibiotic treatment should be reserved for wounds that show signs of infection.

Question 16

The etiologic agent that causes erysipelas is? (check one)
Staphylococcus aureus
Haemophilus influenzae
Streptococcus pyogenes
Pseudomonas aeruginosa
Rubivirus

Answer 16

Streptococcus pyogenes

Erysipelas is caused primarily by group A Streptococcus, with a rare case caused by group C or G. Most cases of erysipelas involve the face, but the lesions can occur anywhere on the body. Penicillin is an effective treatment.

Question 17

Which one of the following basal cell carcinomas is associated with the highest risk of recurrence? (check one)
A 7-mm lesion on the nose
A 9-mm lesion on the forehead
A 12-mm lesion on the shoulder
A 17-mm lesion on the arm

Answer 17

A 7-mm lesion on the nose

Treating basal cell carcinoma with Mohs micrographic surgery leads to the lowest recurrence rate. Because of its cost and limited availability, however, this procedure should be limited to tumors with a higher risk for recurrence. Risk factors include larger size, more invasive histologic subtypes (micronodular, infiltrative, and morpheaform), and sites associated with a higher risk of recurrence.

High-risk locations include the “mask” areas of the face, which include the central face, eyelids, eyebrows, periorbital area, nose, lips (cutaneous and vermilion), chin, mandible, preauricular and postauricular skin/sulci, temple, and ear. Other high-risk sites include the genitalia, hands, and feet. Moderate-risk locations include the cheeks, forehead, scalp, and neck. All other areas, including the trunk and extremities, are low-risk areas.

Even with a low-risk location, a lesion that is ≥20 mm in size has a high risk of recurrence. With a moderate-risk location a lesion ≥10 mm in size carries a higher risk of recurrence, and a lesion ≥6 mm in size is considered high risk in a high-risk location.

Question 18

Which one of the following is an appropriate treatment for tinea capitis? (check one)
Oral cephalosporins
Oral griseofulvin
Topical acyclovir (Zovirax)
Topical ketoconazole (Nizoral)
Topical miconazole (Monistat)

Answer 18

Oral griseofulvin

Tinea capitis is an infection of the scalp caused by a variety of superficial dermatophytes. The treatment of choice for this infection is oral griseofulvin. It has the fewest drug interactions, a good safety record, and anti-inflammatory properties. Terbinafine has equal effectiveness and requires a significantly shorter duration of therapy, but it is only available in tablet form. Since tinea capitis most commonly occurs in children, tablets would have to be cut and/or crushed prior to administration. Oral itraconazole, fluconazole, and ketoconazole have significant side effects. Topical antifungals such as ketoconazole and miconazole are ineffective against tinea capitis. Topical acyclovir is used in the treatment of herpesvirus infections, and oral cephalosporins are used in the treatment of bacterial skin infections.

Question 19

Which one of the following organisms is the most common cause of cutaneous infections associated with intertrigo? (check one)
Candida albicans
Pseudomonas aeruginosa
Staphylococcus aureus
Group A β-hemolytic Streptococcus
Trichophyton mentagrophytes

Answer 19

Candida albicans

Intertrigo is skin inflammation caused by skin-on-skin friction. It is facilitated by moisture trapped in deep skinfolds where air circulation is limited. When intertrigo does not respond to usual conservative measures, including keeping the skin clean and dry, evaluation for infection is recommended. A Wood’s light examination, KOH preparation, and exudate culture can assist in identifying causative organisms.
The moist, damaged skin associated with intertrigo is a fertile breeding ground for various microorganisms, and secondary cutaneous infections are commonly observed in these areas. Candida is the organism most commonly associated with intertrigo. In the interdigital spaces dermatophytes (e.g., Trichophyton rubrum, Trichophyton mentagrophytes, Epidermophyton floccosum) are more common. Staphylococcus aureus may present alone or with group A β-hemolytic Streptococcus (GABHS). Pseudomonas aeruginosa, Proteus mirabilis, or Proteus vulgaris also may occur alone or simultaneously.

Question 20

A mother brings her 10-year-old son to your office because he has recently experienced a flare-up of atopic dermatitis, including increased pruritus. Physical findings include increased erythema of the involved skin on the flexural surfaces of his arms and legs, with weeping eruptions located within areas of lichenification.

Which one of the following topical treatments for managing this episode is supported by the best available evidence? (check one)
Emollients
Pimecrolimus (Elidel)
Mupirocin (Bactroban)
Corticosteroids
Antihistamines

Answer 20

Corticosteroids

Emollients are a mainstay of chronic therapy for atopic dermatitis (SOR C), but topical corticosteroids are the first-line treatment for flare-ups (SOR A). Calcineurin inhibitors such as pimecrolimus are a second-line treatment for moderate to severe atopic dermatitis (SOR A). Antibiotics are not useful in reducing flare-ups of atopic dermatitis unless there is clear evidence of a secondary infection (SOR A). Neither topical nor oral antihistamines are recommended for routine treatment of atopic dermatitis because they are not effective in treating the associated pruritus.

Question 21

Human parvovirus B19 is associated with which one of the following? (check one)
Erythema marginatum
Erythema multiforme
Erythema toxicum
Erythema infectiosum
Erythema chronicum

Answer 21

Erythema infectiosum

Parvovirus B19 is associated with erythema infectiosum, or fifth disease. It is also associated with nonspecific fever, arthropathy, chronic anemia, and transient aplastic crisis.

Question 22

Which one of the following is associated with a herald patch?

(check one)
Pityriasis alba
Pityriasis lichenoides
Pityriasis rosea
Pityriasis rubra pilaris
Pityriasis (tinea) versicolor

Answer 22

Pityriasis rosea

In 50%–90% of patients, pityriasis rosea starts with an erythematous, scaly, oval patch a few centimeters in diameter. This is usually followed within a few days by smaller patches on the trunk and sometimes the proximal extremities. Pityriasis rubra pilaris is a rare disease with five types. The classic adult type begins with a small red plaque on the face or upper body that gradually spreads to become a generalized eruption. The other conditions listed typically begin with multiple lesions.

Question 23

A 40-year-old female presents with several pruritic, thickened, scaly areas on her lower back, knees, and elbows. She says that when she tries to remove the scales they often bleed.

Which one of the following would be the most appropriate pharmacologic therapy for this patient? (check one)
Clobetasol propionate 0.05% lotion (Clobex)
Selenium sulfide 2.5% lotion
Permethrin cream (Nix)
Terbinafine cream 1%
Loratadine (Claritin), 10 mg daily

Answer 23

Clobetasol propionate 0.05% lotion (Clobex)

This patient has psoriasis that is characterized by plaques on her extensor extremities and limited bleeding with removal of the scales (Auspitz sign). First-line treatment for localized plaques is topical corticosteroid therapy, such as clobetasol propionate lotion. Antifungals such as selenium sulfide lotion and terbinafine cream are used to treat dermatophytosis infections including tinea pedis and tinea versicolor. Permethrin cream is indicated for treatment of scabies and lice. Loratadine, an oral antihistamine, is used to treat urticaria.

Question 24

A 64-year-old male comes to your office for evaluation of a persistent rash affecting his groin. It is itchy but not painful and does not affect his daily activities. He has tried over-the-counter antifungal creams without relief. On examination you find well-demarcated, dark red patches in the inguinal region bilaterally. When examined with a Wood’s light the area fluoresces coral-red.

The most effective treatment for this condition is topical?
(check one)
Ketoconazole (Nizoral)
Erythromycin
Hydrocortisone
Mupirocin (Bactroban)
Terbinafine (Lamisil)

Answer 24

Erythromycin

Coral-red fluorescence on Wood’s light examination is typical of infection with Corynebacterium minutissimum, a condition known as erythrasma. This organism commonly complicates intertrigo, often in the groin or interdigital spaces. Erythromycin is the most effective treatment for this bacterial infection.

Question 25

A 14-year-old male has open and closed comedones without evidence of surrounding inflammation on his face and upper back. Which one of the following is the most appropriate initial treatment?

(check one)
Topical antibiotics
Topical retinoids
Oral antibiotics
Oral isotretinoin

Answer 25

Topical retinoids

Comedones are noninflammatory acne lesions. Inflammatory lesions include papules, pustules, and nodules. Grading acne based on the type of lesion and severity helps guide therapy. Topical retinoids prevent the formation of comedones and reduce their number, and are indicated as monotherapy for noninflammatory acne. Topical antibiotics are used primarily for the treatment of mild to moderate inflammatory or mixed acne. Oral antibiotics are effective for the treatment of moderate to severe acne. Oral isotretinoin is reserved for treatment of severe, recalcitrant acne.

Question 26

A 22-year-old primigravida presents for routine prenatal care at 18 weeks gestation. She is frustrated because of increased pigmentation on her face consistent with melasma (chloasma).

Which one of the following would you recommend for this patient?
(check one)
Use of a high-potency broad-spectrum sunscreen
Use of hydroquinone for 4 weeks
Postpartum use of oral contraceptives
Avoiding future use of topical retinoids
Increased surveillance for skin cancer beginning at age 40

Answer 26

Use of a high-potency broad-spectrum sunscreen

Melasma is a very common condition in pregnancy and is due to hyperpigmentation related to normal hormonal changes that accompany pregnancy. It can also be caused by oral contraceptives and is more common in dark-skinned persons.
High-potency broad-spectrum sunscreens may help prevent melasma, or at least prevent worsening of the condition (SOR C). Topical retinoids, hydroquinone, and corticosteroids can also be helpful, but are usually reserved for postpartum use and require months of treatment. Other treatments include azelaic acid, chemical peels, kojic acid, cryosurgery, and laser treatment (SOR B). Melasma usually improves spontaneously after delivery, but it may be prolonged or worsened by oral contraceptive use. It does not increase the risk of developing skin malignancies.

Question 27

Which one of the following accurately describes the classic rash of erythema migrans? (check one)
Scattered individual purple macules on the ankles and wrists
An annular rash with a bright red outer border and partial central clearing
A dry, scaling, dark red rash in the groin, with an active border and central clearing
A diffuse eruption with clear vesicles surrounded by reddish macules
A migratory pruritic, erythematous, papular eruption

Answer 27

An annular rash with a bright red outer border and partial central clearing

An annular rash with a bright red outer border and partial central clearing is characteristic of erythema migrans. It is important to remember that not all lesions associated with Lyme disease look this way, and that some patients with Lyme disease may not have any skin lesions at all. Rocky Mountain spotted fever causes scattered individual purple macules on the ankles and wrists. A dry, scaling, dark red rash in the groin, with an active border and central clearing, is seen with tinea cruris. A diffuse eruption with clear vesicles surrounded by reddish macules is found in chickenpox. A migratory pruritic, erythematous, papular eruption is most consistent with urticaria.

Question 28

A 50-year-old male presents to your office with erythroderma and fever. He has not had a sore throat, rhinorrhea, cough, or urinary tract symptoms. His current medications include lisinopril (Prinivil, Zestril), atenolol (Tenormin), and allopurinol (Zyloprim). On examination he has a blood pressure of 110/90 mm Hg, a pulse rate of 90 beats/min, and a temperature of 38.6°C (101.5°F). The skin is remarkable for marked erythema over 90% of the body, with tenderness to touch. His mental status is clear and his neck is supple. Mildly tender adenopathy is noted in the neck, axillae, and groin. He has no oral ulcerations or ocular symptoms.
A CBC shows a WBC count of 15,000/mm3 (N 4300–10,800) with 20% eosinophils. A metabolic profile shows an AST (SGOT) level of 100 U/L (N 10–40) and an ALT (SGPT) level of 110 U/L (N 10–55), but is otherwise normal.
Which one of the following is the most likely diagnosis?
(check one)
Stevens-Johnson syndrome
Erysipelas
Red man syndrome
Toxic shock syndrome
Drug reaction with eosinophilia and systemic symptoms (DRESS syndrome)

Answer 28

Drug reaction with eosinophilia and systemic symptoms (DRESS syndrome)

DRESS is an acronym for Drug Reaction with Eosinophilia and Systemic Symptoms. The hallmark of DRESS syndrome is erythroderma accompanied by fever, lymphadenopathy, elevation of liver enzymes, and eosinophilia. The offending medication should be discontinued immediately and treatment with corticosteroids should be initiated. Seizure medications such as carbamazepine, phenytoin, lamotrigine, and phenobarbital are responsible for approximately one-third of cases. Allopurinol-associated DRESS syndrome has the highest mortality rate.

Stevens-Johnson syndrome is characterized by a vesiculobullous rash with mucocutaneous involvement, and erysipelas is a painful localized rash with well-demarcated borders. Red man syndrome is associated with vancomycin.

Question 29

Electrosurgical destruction is contraindicated for which one of the following skin lesions? (check one)
Cherry angiomata
Pyogenic granuloma
Basal cell carcinoma
Melanoma
Actinic keratosis

Answer 29

Melanoma

Contraindications to treatment with electrosurgery include the use of a pacemaker and the treatment of melanoma. All the other lesions listed can be treated with electrosurgery.

Question 30

The presence of nonthrombocytopenic palpable purpura, colicky abdominal pain, and arthritis is most consistent with which one of the following? (check one)
Kawasaki disease
Takayasu arteritis
Wegener granulomatosis
Polyarteritis nodosa
Henoch-Schonlein purpura

Answer 30

Henoch-Schonlein purpura

The most common pediatric vasculitis is Henoch-Schonlein purpura. It is an IgA-mediated small-vessel vasculitis that classically presents with the triad of nonthrombocytopenic palpable purpura, colicky abdominal pain, and arthritis. Kawasaki disease is manifested by conjunctival injection, mucosal erythema, rash, and lymphadenopathy. Takayasu arteritis has numerous manifestations, including night sweats, fatigue, weight loss, myalgia, and arthritis. Later findings may include hypertension, skin lesions, and cardiac disorders. Wegener granulomatosis causes constitutional symptoms also, including weight loss and fatigue, with later findings including respiratory problems, ophthalmologic lesions, neuropathies, glomerulonephritis, and skin lesions. Polyarteritis nodosa is another disease that causes constitutional symptoms such as fatigue, fever, and myalgias. It also causes skin lesions, gastrointestinal symptoms such as postprandial abdominal pain, and cardiac lesions.

Question 31

A 59-year-old female with type 2 diabetes develops a 2x1-cm ulcer on the plantar aspect of her right foot. The ulcer is very deep and there is surrounding cellulitis. A plain film is normal. Which one of the following would be the imaging study of choice to rule out osteomyelitis in this patient? (check one)
Angiography
A CT scan
An MRI scan
A PET scan
A leukocyte scan

Answer 31

An MRI scan

Although leukocyte scans are sensitive for the diagnosis of foot ulcers, MRI is now considered the imaging study of choice when osteomyelitis is suspected; the sensitivity and specificity of MRI in diabetic patients are 90% or greater.

Question 32

A 53-year-old female is concerned about a skin lesion that has recently been changing in size and shape. On examination she is found to have a 7-mm, asymmetric, darkly pigmented lesion with some color variegation and irregular borders.

Which one of the following skin biopsy techniques is most appropriate for confirming the diagnosis? (check one)
A shave biopsy
Electrodesiccation and curettage
Elliiptical excision
Mohs surgery

Answer 32

Elliiptical excision

This lesion is suspicious for melanoma, based on the asymmetry, irregular border, color variegation, and size larger than 6 mm. In addition, a history of evolution of the lesion, with changes in size, shape, or color, has been shown in some studies to be the most specific clinical finding for melanoma. The preferred method of biopsy for any lesion suspicious for melanoma is complete elliptical excision with a small margin of normal-appearing skin. The depth of the lesion is crucial to staging and prognosis, so shave biopsies are inadequate. A punch biopsy of the most suspicious-appearing area is appropriate if the location or size of the lesion makes full excision inappropriate or impractical, but a single punch biopsy is unlikely to capture the entire malignant portion in larger lesions. Electrodesiccation and curettage is not an appropriate treatment for melanoma. Mohs surgery is sometimes used to treat melanomas, but is not used for the initial diagnosis.

Question 33

A 70-year-old white female presents with a pruritic rash on her sacrum that has occurred intermittently over the last 6 years. She reports that the area is always very tender just before the blister-like lesions erupt. She is otherwise in good health, and takes no medications. Her past medical history is unremarkable. You provide appropriate treatment for the condition. You should advise the patient to avoid which one of the following during future outbreaks? (check one)
Excessive intake of green, leafy vegetables
Sexual contact
Perfumed soaps or body lotions
Sun exposure
Prolonged sitting

Answer 33

Sexual contact

Genital herpes is the most common sexually transmitted genital ulcer disease in the U.S. It can occur at any age, and data suggest that it may be the most common sexually transmitted disease in women over the age of 50 years. Extragenital sites are involved in one-fourth of infected women, and the sacrum and buttocks are frequent locations. Sacral nerve innervation from the vaginal area provides a pathway for the virus. Prevention of transmission depends upon cogent patient education advising abstinence from skin-to-skin contact when active lesions are present.

Question 34

A 65-year-old white female develops a burning pain in the left lateral thorax, followed 2 days later by an erythematous vesicular rash. Of the following, the best treatment is: (check one)
Topical corticosteroids
Oral corticosteroids
Topical acyclovir (Zovirax)
Oral valacyclovir (Valtrex)
Topical capsaicin (Zostrix)

Answer 34

Oral valacyclovir (Valtrex)

The rash described is typical of herpes zoster. This commonly occurs in older individuals who have had chickenpox in childhood. The treatment of choice for acute herpes zoster is oral antiviral agents. Acyclovir, valacyclovir, and famciclovir have all been shown to be efficacious with 7 days of oral treatment. Studies suggest that valacyclovir may be superior to acyclovir in decreasing both acute and postherpetic pain. Famciclovir appears to be equal in efficacy to valacyclovir. Topical acyclovir may be effective for more limited forms of herpes simplex, but is usually not effective for herpes zoster. Topical and oral corticosteroids may have some use for combatting the inflammatory process, and may decrease the incidence of postherpetic neuralgia in certain individuals. Topical capsaicin may be useful in treating the pain of acute herpes zoster infection, as well as postherpetic neuralgia.

Question 35

A 5-year-old female presents with a lesion on her forearm. It began as a red macule, turned into a small vesicle that easily ruptured, then dried into a 1-cm honey-colored, crusted lesion seen now. Which one of the following would be the most appropriate therapy? (check one)
Oral penicillin V
Oral erythromycin
Topical disinfectant (e.g., hydrogen peroxide)
Topical bacitracin
Topical mupirocin (Bactroban)

Answer 35

Topical mupirocin (Bactroban)

Topical mupirocin is as effective as cephalexin or amoxicillin/clavulanate in the treatment of impetigo, which is most often caused by Staphlococcal species. Oral penicillin V, oral erythromycin, and topical bacitracin are less effective than mupirocin. Topical treatment is well suited to this localized lesion. Topical disinfectants such as hydrogen peroxide are no more effective than placebo

Question 36

An otherwise healthy 70-year-old male presents with a 6-month history of hives recurring every week or so. A causative factor is not identified through the history and physical examination.

Which one of the following is recommended as the first-line treatment for this patient’s chronic urticaria? (check one)
A first-generation H1-antihistamine
A second-generation H1-antihistamine
An H2-antihistamine
Omalizumab (Xolair)
Prednisone

Answer 36

A second-generation H1-antihistamine

A stepwise method is recommended for the treatment of chronic urticaria of unknown cause. The first step is the regular use of a second-generation H1-antihistamine. An increase of up to four times the approved dosage is safe and may be helpful as part of step two. If the urticaria is still poorly controlled, an H2-antihistamine or antileukotriene agent may be added in step two. Systemic corticosteroids can be used for short-term control of severe acute episodes, but long-term use should be avoided. First-generation H1-antihistamines can be used if control cannot be achieved at step two, but they should be used cautiously, as sedation and confusion may occur, especially in the elderly. The options available in the third step of treatment are omalizumab and cyclosporine.

Question 37

A 40-year-old male presents because he is losing large clumps of hair when he brushes or washes it. He feels well otherwise and does not take any medications. His past medical history is unremarkable except for a cholecystectomy 4 months ago for acute cholecystitis. A physical examination is normal except for uniform, diffuse thinning of the hair on his scalp. You do not observe any patches of hair loss, redness, inflammation, scaling, or scarring of his scalp.

Which one of the following would be the most appropriate next step in managing this patient’s hair loss? (check one)
Reassurance only
Cognitive behavioral therapy
Terbinafine
Intracutaneous scalp corticosteroid injections

Answer 37

Reassurance only

There are three phases of hair growth: the anagen, or growth phase; the catagen, or degeneration phase; and the telogen, or resting phase. It is during the telogen phase that hair sheds. This patient has telogen effluvium in which diffuse, not patchy, hair loss is caused by large numbers of hairs entering the telogen phase and falling out 3–5 months after a stressor. The stress may be emotional or physiologic, such as this patient’s acute cholecystitis with cholecystectomy. A history of hair coming out in clumps is suggestive of this diagnosis. The incidence is similar among age groups and sexes. Telogen effluvium is usually self-limited and resolves within 2–6 months. The treatment is reassurance.

Cognitive behavioral therapy is used to treat trichotillomania, an impulse-control disorder in which patients pull, twist, or twirl hair, typically in the frontoparietal area. It can include the eyelashes and eyebrows. Terbinafine is an antifungal that can be used to treat tinea capitis, a patchy dermatophyte infection of the hair shaft and follicles that is associated with itching, scaling, and pustules. Intralesional corticosteroids can be used for alopecia areata where the hair loss pattern is patchy or involves the entire scalp. It can also involve the entire body. The hair loss is more gradual in this condition.

Question 38

A 25-year-old female presents with a maculopapular rash that has progressed to multiple areas and exhibits target lesions. A cold sore appeared on her upper lip 2 days before the rash appeared. She is not systemically ill and is on no medications.
Which one of the following is true concerning this problem?
(check one)
Herpes simplex virus is a likely cause
A skin biopsy will confirm the diagnosis
The lesions usually disappear within 24 hours
The palms of the hands and soles of the feet are not involved
Scarring from the lesions is often seen after resolution

Answer 38

Herpes simplex virus is a likely cause

Herpes simplex virus is the most common etiologic agent of erythema multiforme. Other infections, particularly Mycoplasma pneumoniae infections and fungal infections, may also be associated with this hypersensitivity reaction. Other causes include medications and vaccines. Skin biopsy findings are not specific for erythema multiforme. As opposed to the lesions of urticaria, the lesions of erythema multiforme usually are present and fixed for at least 1 week and may evolve into target lesions. The palms of the hands and soles of the feet may be involved. The lesions of erythema multiforme usually resolve spontaneously over 3–5 weeks without sequelae

Question 39

A 24-year-old male presents for evaluation of a soft-tissue mass on his arm. Which one of the following features, if present, should prompt further evaluation with advanced imaging? (check one)
Diameter ≥5 cm
Fluctuant texture
Lack of tenderness with palpation
Persistent, slow growth over several years
Superficial location (above the fascia)

Answer 39

Diameter ≥5 cm

Soft-tissue masses that are 5 cm in diameter carry a higher risk of malignancy and should prompt further evaluation with advanced imaging. Other features that raise concern for possible malignancy include rapid growth, sudden presentation without explanation, and lesions that are firm, deep, and adhere to surrounding structures. Both benign and malignant masses can be painless, but a lack of tenderness with palpation alone would not prompt the need for advanced imaging. Advanced imaging would also not be necessary for a mass that has a fluctuant texture, has grown persistently and slowly over several years, or is superficially located (above the fascia).

Question 40

Three days after a camping trip in New Hampshire a patient develops influenza-like symptoms of a fever, mild myalgias, and malaise followed by an expanding, erythematous, annular rash with central clearing on his thigh. Which one of the following is the most likely diagnosis for the rash? (check one)
Erythema migrans
Erythema multiforme
Nummular eczema
Pityriasis rosea
Tinea corporis

Answer 40

Erythema migrans

Annular lesions can be a presentation of several different conditions. This patient’s history of possible tick exposure and current prodromal constitutional symptoms suggest acute Lyme disease. Erythema migrans is the characteristic rash of acute Lyme disease. Erythema multiforme can be spontaneous, related to a viral or Mycoplasma infection, or associated with a medication reaction. Prodromal symptoms are uncommon in limited erythema multiforme and the clinical context of this case suggests a different etiology. Nummular eczema is an intensely pruritic, annular lesion that is not associated with constitutional symptoms. Pityriasis rosea is thought to be viral in etiology and is usually otherwise asymptomatic. Tinea corporis is a fungal infection and is not associated with systemic symptoms.

Question 41

You see a 47-year-old female for follow-up of a rash. She is a carpenter and was seen 4 days ago for increasing redness and tenderness of her anterior shin after hitting the area with a board 3 days earlier. She was afebrile during that visit and the area was red but not fluctuant. She chose observation rather than treatment at that time. The patient smokes 10 cigarettes daily. Past medical, surgical, and family histories are otherwise negative. Screening for diabetes mellitus was normal last year.

Today the patient’s anterior shin is still tender. She is afebrile and other vital signs are unremarkable. The extent of the infection was drawn 4 days ago with an indelible marker by your partner. Currently the area of redness extends beyond this border. There is no fluctuance or drainage of the wound. The skin appears mildly indurated.

Which one of the following would be best to provide coverage against Streptococcus pyogenes or methicillin-resistant Staphylococcus aureus (MRSA) in this patient? (check one)
Amoxicillin/clavulanate (Augmentin) and ciprofloxacin (Cipro)
Cephalexin and dicloxacillin
Dicloxacillin and fosfomycin (Monurol)
Doxycycline and trimethoprim/sulfamethoxazole (Bactrim)
Trimethoprim/sulfamethoxazole and cephalexin

Answer 41

Trimethoprim/sulfamethoxazole and cephalexin

Clindamycin or a combination of trimethoprim/sulfamethoxazole (or doxycycline or minocycline) plus cephalexin (or dicloxacillin or amoxicillin/clavulanate) should provide adequate coverage for Streptococcus and methicillin-resistant Staphylococcus aureus (MRSA) for mild to moderate cellulitis.

Doxycycline plus trimethoprim/sulfamethoxazole would provide inadequate coverage for streptococcal bacteria. Cephalexin plus dicloxacillin would provide inadequate coverage for MRSA. The primary indication for ciprofloxacin is treatment of infections with gram-negative rods. Fosfomycin is indicated only for urinary tract infections. Neither is typically used in the treatment of cellulitis.

Question 42

A 32-year-old female sees you for evaluation of hair loss. On examination she has a smooth, circular area of complete hair loss on her scalp with no other skin changes.

Which one of the following would you recommend? (check one)
An oral antifungal agent
Topical minoxidil (Rogaine)
Topical immunotherapy
Topical corticosteroids
Intralesional corticosteroids

Answer 42

Intralesional corticosteroids

This patient has alopecia areata, which is a chronic, relapsing, immune-mediated inflammatory disorder affecting hair follicles that results in patchy hair loss. The treatment of choice is intralesional corticosteroid injections. Topical immunotherapy is reserved for patients with extensive disease, such as >50% scalp involvement. Topical corticosteroids are less effective and are usually reserved for children and adults who cannot tolerate intralesional injections. Minoxidil is used for androgenetic alopecia and is less effective for alopecia areata. Oral antifungal drugs are used to treat tinea capitis.

Question 43

A previously healthy 6-year-old male is brought to your office because he has a fever. After a complete history and physical examination you are concerned that the child has Rocky Mountain spotted fever.

Which one of the following would be the most appropriate management? (check one)
Supportive care only
Amoxicillin
Doxycycline
Rifampin (Rifadin)

Answer 43

Doxycycline

The treatment of Rocky Mountain spotted fever (RMSF) must be started as soon as the diagnosis is suspected in order to decrease mortality. Doxycycline is the only approved therapy for RMSF for individuals of all ages, including children <8 years of age. Of the other options listed, only rifampin and chloramphenicol have been used for the treatment of RMSF, but they are not FDA approved.

Providing supportive care or waiting for confirmation of the diagnosis would not be appropriate. Laboratory tests such as a CBC and chemistries can be helpful in looking for other causes of a patient’s symptoms but findings will not be specific for RMSF. Serologies may be helpful but are not available immediately and may be negative early in the disease process.

Question 44

A 26-year-old male presents with a rash on his anterior neck in the area of his beard that has been present for over a year. On examination he has dark, curly facial hair, and you find slightly tender, red, hyperpigmented papules on the superior anterior neck.

Which one of the following would you recommend to improve this patient’s rash? (check one)
Shaving with a multi-blade razor
Shaving with electric clippers
Pulling the skin taut while shaving
Plucking hairs rather than shaving
Oral cephalexin (Keflex)

Answer 44

Shaving with electric clippers

This patient has pseudofolliculitis barbae, which is a common condition affecting the face and neck in people with tightly curled hair. The condition occurs when hairs are cut at an angle and curl in on themselves, creating a foreign body reaction. The condition may progress to scarring and keloid formation. Cessation of hair removal improves the condition. If this is not desired, less aggressive hair trimming is recommended. Clippers generally result in a less close shave and contribute less to pseudofolliculitis barbae. Multi-blade razors, pulling the skin taut, and plucking hairs all result in shorter hair and are likely to exacerbate the problem. The description of the rash is not consistent with secondary infection, so oral cephalexin would not be indicated at this time. Treatment is similar to the treatment of acne, with benzoyl peroxide, topical retinoids, and topical antibiotics having a role, along with topical corticosteroids.

Question 45

A 46-year-old female with a past medical history of polycystic ovary syndrome and migraine headaches presents with bilateral, hyperpigmented patches along her mandible. The patches are asymptomatic but bother her cosmetically and seem to be darkening.

Which one of her medications would be most likely to contribute to her melasma? (check one)
B-complex vitamins
Metformin (Glucophage)
Oral contraceptives
Spironolactone (Aldactone)
Sumatriptan (Imitrex)

Answer 45

Oral contraceptives

Melasma is a progressive, macular, nonscaling hypermelanosis of skin exposed to the sun, typically involving the face and dorsal forearms. It is often associated with pregnancy and the use of oral contraceptives or anticonvulsants (SOR C). Some melasma is idiopathic. Women are nine times more likely to be affected than men, and darker-skinned individuals are also at greater risk. There are three common patterns of melasma: centrofacial, malar, and mandibular.

Question 46

An elderly male presents with a shallow, irregularly shaped ulceration over the medial aspect of his right lower leg between the lower calf and medial malleolus. There is some surrounding edema with pigment deposition over the lower leg. He reports aching and burning pain in the lower leg with daytime swelling. His symptoms improve with leg elevation.

You make a diagnosis of venous stasis ulcer. Which one of the following would be the most appropriate management? (check one)
The use of foam dressings rather than other standard dressings
The use of silver-based antiseptic products even if there is no infection
Compression therapy
A 3-week course of systemic antibiotics

Answer 46

Compression therapy

This patient likely has a venous stasis ulceration. The use of compression therapy with a pressure of 30–40 mm Hg is the mainstay of treatment. There is no evidence for the use of systemic antibiotics for lower-extremity ulcerations. Likewise, there is no evidence to support the use of either silver-based or honey-based preparations in ulcerations with no infection. Foam dressings are no more effective than other standard dressings.

Question 47

A 52-year-old male presents for evaluation of a long-standing facial rash. He reports that the rash is itchy, with flaking and scaling around his mustache and nasolabial folds.

Which one of the following is most likely to be beneficial? (check one)
Topical antibacterial agents
Topical antifungal agents
Topical vitamin D analogues
Oral zinc supplementation

Answer 47

Topical antifungal agents

Seborrheic dermatitis is commonly seen in the office setting and affects the scalp, eyebrows, nasolabial folds, and anterior chest. The affected skin appears as erythematous patches with white to yellow greasy scales. The etiology is not exactly known, but it is likely that the yeast Malassezia plays a role. Topical antifungals are effective and recommended as first-line agents. Topical low-potency corticosteroids are also effective alone or when used in combination with topical antifungals, but they should be used sparingly due to their adverse effects. The other agents listed have no role in the management of seborrheic dermatitis (SOR A).

Question 48

A 13-year-old male is brought to your office because of pain in his foot. Two days ago he stepped on a nail that went through his sneaker and caused a puncture wound to the base of his foot. On examination today he has tenderness and erythema surrounding the wound, and you can express pus from the wound. He is afebrile.

Which one of the following would be best to treat this patient’s cellulitis? (check one)
Amoxicillin/clavulanate (Augmentin)
Cephalexin (Keflex)
Ciprofloxacin (Cipro)
Doxycycline
Trimethoprim/sulfamethoxazole (Bactrim)

Answer 48

Ciprofloxacin (Cipro)

Puncture wounds to the foot commonly get infected. Most soft-tissue infections from puncture wounds are caused by gram-positive organisms. Staphylococcus aureus is the most common, followed by other staphylococcal and streptococcal species. When the puncture wound is through the rubber sole of an athletic shoe, Pseudomonas is the most frequent pathogen. Ciprofloxacin is the only oral antibiotic that has antipseudomonal activity, and would be the most appropriate choice.

Question 49

A 15-year-old female comes to your office for treatment of acne vulgaris. Her complete history and physical examination are unremarkable other than a moderate amount of closed comedones and inflamed papules on her nose, forehead, and upper back. She has not previously tried any topical or oral therapies, including over-the-counter medications.

Which one of the following would be indicated for this patient as monotherapy? (check one)
Topical benzoyl peroxide
Topical clindamycin (Cleocin T)
Oral isotretinoin (Absorica)
Oral minocycline (Minocin)
Oral spironolactone (Aldactone)

Answer 49

Topical benzoyl peroxide

Oral antibiotics are recommended for acne that is resistant to topical treatments. Oral isotretinoin is indicated for severe nodular acne or moderate acne resistant to other treatments. Since this patient has not tried any therapies, these two options would not yet be appropriate. Topical antibiotics are recommended only in combination with benzoyl
peroxide. Appropriate treatments would be topical benzoyl peroxide, a topical retinoid, and oral contraceptives. Antiandrogen therapies such as spironolactone are not indicated solely for acne vulgaris, although they may be appropriate for concomitant conditions such as polycystic ovary syndrome.

Question 50

A 2-year-old male has a 3-day history of a runny nose and cough, and a 2-day history of fever reaching 40.0°C (104.0°F). He woke up with a rash this morning. His appetite is good and his activity level is normal. On examination the child is afebrile with normal vital signs, and has a fine, maculopapular, erythematous rash on the trunk and extremities. The remainder of the examination is normal.

Which one of the following is the most likely cause of this patient’s rash? (check one)
Atopic dermatitis
Erythema infectiosum
Molluscum contagiosum
Pityriasis rosea
Roseola infantum

Answer 50

Roseola infantum

This patient has the classic presentation for roseola infantum, which is caused by human herpesvirus 6. The typical history includes a high fever in a child with either mild upper respiratory symptoms or no other symptoms. After the fever subsides, a rash will appear. The rash is self-limited and no treatment is required.

Pityriasis rosea typically presents with a single herald patch that is oval-shaped and scaly with central clearing, followed by a symmetric rash on the trunk in a typical distribution along the Langer lines. The rash may last up to 12 weeks and no treatment is required.

Erythema infectiosum is caused by parvovirus B19 and is also known as fifth disease. The child will typically have mild symptoms then an erythematous facial rash that has a “slapped cheek” appearance. This is sometimes followed by pink patches and macules in a reticular pattern. Once the rash appears the child is no longer contagious.

Molluscum contagiosum is caused by a poxvirus and is characterized by scattered flesh-colored papules with umbilicated centers. Atopic dermatitis typically presents as scaly, erythematous plaques, commonly on the flexor surfaces of the extremities.

Question 51

A 45-year-old female visits your office for her annual health maintenance visit and mentions that her hair has been thinning over the past few years. She is now concerned that it may be noticeable. She takes no medications and is otherwise healthy with normal menstrual cycles. On examination she has a negative pull-away test. You note diffuse thinning in the parietal regions, with sparing of the frontal hairline. She has no scalp scarring, scale, or erythema.

Which one of the following would be the most appropriate pharmacotherapy? (check one)
Finasteride (Propecia), 1 mg daily
Griseofulvin, 500 mg daily
Hydroxychloroquine (Plaquenil), 200 mg twice daily
Minoxidil 2% (Rogaine), applied to the scalp twice daily
Triamcinolone 0.05% (Trianex), applied to the scalp twice daily

Answer 51

Minoxidil 2% (Rogaine), applied to the scalp twice daily

Female pattern hair loss is categorized as diffuse and nonscarring. It presents with parietal hair thinning with preservation of the frontal hairline. Minoxidil 2% produces regrowth of hair in female pattern hair loss (SOR B). Oral finasteride is appropriate only for men with male pattern hair loss (SOR A). Hydroxychloroquine is used for inflammatory hair loss associated with discoid lupus erythematosus, which is focal and scarring. Topical corticosteroids are appropriate for alopecia areata (SOR B) but not for female pattern hair loss. Griseofulvin is used to treat tinea capitis, which presents as focal scale with erythema.

Question 52

A 2-year-old female is brought to your office because of a round lesion on her lip that appeared 2 days ago. Her temperature and all vital signs are normal. She has no past medical history and takes no medications. Further history reveals that she was playing with a toy trumpet in a busy store a few days before the lesion appeared. A physical examination reveals a 1-cm round lesion with crusting, and no other skin abnormalities.

Which one of the following would be the best treatment at this time? (check one)
Bacitracin
Mupirocin (Bactroban)
Neomycin
Cephalexin (Keflex)
Clindamycin (Cleocin)

Answer 52

Mupirocin (Bactroban)

This patient has physical findings and a history consistent with impetigo, a skin infection caused by Staphylococcus aureus and/or Streptococcus pyogenes . Since she has only one lesion, systemic antibiotics are not required as they would be for a patient with extensive disease or multiple lesions. Although bacitracin and neomycin are commonly used, they are much less effective for impetigo than mupirocin, despite some reports of resistance to mupirocin (level A-1 evidence).

Question 53

A mother who recently immigrated to the United States from Mexico brings her 4½-year-old son to your clinic for his pre-kindergarten examination. The child’s examination is normal except for a hemangioma located on his left arm. His mother says that the lesion appeared at about 4 weeks of age, continued to grow until he was about 5 months of age, and then began to flatten, shrink, and fade. She is concerned because it has not improved in the past 18 months. When you examine the lesion more closely you note telangiectasia, fibrofatty tissue, dyspigmentation, and scarring where involution has occurred.

Which one of the following would be the most appropriate management? (check one)
Oral propranolol
Corticosteroid injection
Referral for laser therapy
Referral for surgical excision

Answer 53

Referral for surgical excision

Infantile hemangiomas usually appear by 4 weeks of age and stop growing by 5 months of age. As many as 70% leave residual skin changes, including telangiectasia, fibrofatty tissue, redundant skin, atrophy, dyspigmentation, and scarring. Systemic corticosteroids were the mainstay of treatment for hemangiomas during infancy until 2008, when the FDA approved oral propranolol for this indication. Intralesional corticosteroids can be effective for small, bulky, well localized lesions in infants. Laser therapy can also be used to treat early lesions or residual telangiectasia. Once involution is complete, however, as is the case with this child, elective surgical excision is the treatment of choice, producing better outcomes.

Question 54

A 67-year-old male presents to your office with a 1-month history of fever with edema and erythema of his right foot. His medical history is significant for peripheral artery disease and poorly controlled type 2 diabetes with diabetic neuropathy. Significant vital signs include a temperature of 38.6°C (101.5°F), a blood pressure of 155/90 mm Hg, and a pulse rate of 85 beats/min. A physical examination is most notable for a draining ulcer on the ball of his right foot. The edema and erythema are limited to his right foot and he has no calf tenderness. Dorsalis pedis and posterior tibial artery pulses are present but diminished at the right ankle. Sensation to monofilament testing of his right foot is diffusely diminished, which is consistent with his baseline.

The best initial imaging test of the foot ulcer would be: (check one)
radiography
ultrasonography
CT
MRI
technetium 99m bone scintigraphy

Answer 54

radiography

This patient has osteomyelitis until proven otherwise. A radiograph of his right foot is the best initial test to look for evidence of this diagnosis. In most treatment settings, radiography is much easier to obtain than ultrasonography, CT, MRI, or technetium 99m bone scintigraphy. In addition, it is generally considerably less expensive than the other options listed. A radiograph also allows the physician to rule out other bony pathologies. MRI is useful if the radiograph is inconclusive, and is more helpful than radiography for determining bony versus soft-tissue infection. CT may be used in cases where MRI is contraindicated. Ultrasonography is not useful for evaluating bony lesions. Bone scintigraphy has low sensitivity, particularly in the setting of recent trauma or surgery.

Question 55

A 27-year-old male has been treating his plaque psoriasis with high-potency topical corticosteroids for several years. He comes to your office to discuss other options since the lesions on his trunk and extremities are becoming resistant to this therapy.

Which one of the following treatment strategies would be most appropriate? (check one)
Switch to topical tazarotene (Avage, Tazorac)
Add topical calcipotriene (Dovonex, Sorilux)
Begin oral acitretin (Soriatane)
Begin an oral corticosteroid
Begin etanercept (Enbrel) injections

Answer 55

Add topical calcipotriene (Dovonex, Sorilux)

Oral corticosteroids are not indicated in the treatment of plaque psoriasis. All of the other options are indicated only if topical treatments fail. Of the options listed, the combination of a topical corticosteroid and topical calcipotriene is considered the most appropriate for this patient. Another option would be to add topical tazarotene to the topical corticosteroid. However, when tazarotene is used as monotherapy it often fails to clear plaques and increases the incidence of skin irritation.

Question 56

A 57-year-old female who spends a lot of time working in her yard has pigmented areas on sun-exposed skin. She has several of these and would like to address them for cosmetic reasons. An examination is consistent with solar lentigines. One of these on her posterior leg has increased in size more rapidly.

Which one of the following would be the most appropriate next step for the lesion on the posterior leg? (check one)
Topical hydroquinone (Lustra)
A topical retinoid
Cryotherapy
Laser therapy
A biopsy

Answer 56

A biopsy

Solar lentigines occur on sun-exposed skin and are known commonly as liver spots. A biopsy should be
performed if they grow rapidly, change rapidly, are painful, itch, bleed easily, heal poorly, or have an
atypical or suspicious appearance.
If no suspicious changes or symptoms are present there are various options for treatment, including topical
therapy with hydroquinone or retinoids, or ablative therapy with chemical peels, cryotherapy, intense
pulsed light, or laser therapies.

Question 57

A Black female presents with multiple insect bites on her arms and legs. This patient is at risk for developing which one of the following conditions? (check one)
Acanthosis nigricans
Acne keloidalis nuchae
Dermatosis papulosa nigra
Melasma
Postinflammatory hyperpigmentation

Answer 57

Postinflammatory hyperpigmentation

Patients with dark skin are at greater risk for postinflammatory hyperpigmentation, a reactive hypermelanosis. These are irregular hyperpigmented macules or patches that can occur after endogenous inflammation (e.g., acne vulgaris, pseudofolliculitis barbae, atopic dermatitis, lichen planus, psoriasis, contact dermatitis) and external injuries (e.g., insect bites, chemical peels, cryotherapy, laser surgery). This condition can occur at any age and is particularly noticeable in Fitzpatrick skin phototypes III, IV, V, and VI. Fitzpatrick skin phototype is used to classify the skin color spectrum and is based on an individual’s propensity for sunburn (photodermatitis). It is not a surrogate marker for race or ethnicity. Broad-spectrum, water-based sunscreen with SPF 30 should be used to prevent postinflammatory hyperpigmentation (SOR C). Sunscreen that blocks visible light such as iron oxide is also useful.

Acanthosis nigricans, acne keloidalis nuchae, dermatosis papulosa nigra, and melasma are conditions that are also more common in skin of color. However, they are not related to external injuries such as insect bites. Acanthosis nigricans are usually on the posterior neck, axillae, and groin. These are velvety, irregularly defined, hyperpigmented patches. Acne keloidalis nuchae occur in the nuchal and occipital scalp. These are keloid-like papules, plaques, and cicatricial alopecia. Dermatosis papulosa nigra is usually on the face and neck. They are hyperpigmented, filiform, or sessile papules. Melasma are gray-brown patches that usually occur on the face.

Question 58

A 21-year-old male presents to your office with excessive sweating in the axillae, palms, and soles. This has been a problem for several years and interferes with his ability to participate in daily activities without discomfort and embarrassment. After ruling out possible secondary causes you diagnose primary focal hyperhidrosis.

Which one of the following would you recommend as a first-line treatment? (check one)
Topical 20% aluminum chloride (Drysol)
Topical 2% glycopyrrolate
Oral oxybutynin
Localized application of microwave energy
Sympathetic denervation

Answer 58

Topical 20% aluminum chloride (Drysol)

The recommended first-line treatment for primary focal hyperhidrosis is topical 20% aluminum chloride.
It should be applied to affected areas nightly for 6–8 hours and works by obstructing the eccrine sweat
glands and destroying secretory cells. Iontophoresis and botulinum toxin are alternative first- or second-line
therapies for palmar and plantar hyperhidrosis and hyperhidrosis affecting the axillae, palms, soles, or
face.
Topical 2% glycopyrrolate must be compounded by a pharmacy and is indicated only for craniofacial
hyperhidrosis. Oral anticholinergics such as oxybutynin can be considered if other first-line treatments fail.
However, up to 10% of patients will stop taking these medications due to side effects such as dry mouth,
constipation, urinary retention, and blurred vision. Microwave technology is a newer treatment option that
has shown some promising results but should not be recommended as a first-line treatment. Sympathetic
denervation should be used only if other less invasive therapies have already been tried.

Question 59

A 28-year-old female presents with a 2.5-cm pruritic, erythematous, oval macule on her left thigh. She was seen at an urgent care facility 2 days ago for a urinary tract infection (UTI) and was treated with sulfamethoxazole/trimethoprim (Bactrim). Her UTI symptoms have improved. She reports that she was called earlier this morning and told that her infection was caused by Escherichia coli. The patient reports a similar lesion in the same area about a year ago at the time of her last UTI.

You explain this is most likely secondary to: (check one)
an immunologic reaction to E. coli
erythema multiforme
nummular eczema
the Shiga toxin sometimes produced by E. coli
the sulfamethoxazole/trimethoprim used to treat the infection

Answer 59

the sulfamethoxazole/trimethoprim used to treat the infection

This is a typical history for a fixed drug eruption (FDE), which is an immunologic reaction that recurs upon re-exposure to the offending drug. It is most likely related to T-lymphocytes at the dermal-epidermal junction. Sulfonamides and anticonvulsants are the most frequently cited medications, but tetracycline and penicillins have also been reported to cause FDE. FDE is not caused by bacteria. Erythema multiforme does not present as an isolated, recurrent macule and generally has central clearing. Nummular eczema is a coin-shaped, very pruritic patch but does not fit this clinical scenario. Shiga toxin–producing Escherichia coli are rarely found in extra-intestinal sites.

Question 60

A 30-year-old gravida 1 para 0 develops erythematous patches with slightly elevated scaly borders during her first trimester. There was a 2-cm herald patch 2 weeks before multiple smaller patches appeared. The rash on the back has a “Christmas tree” pattern. She has not had any prenatal laboratory work.

This condition is associated with (check one)
no additional pregnancy risk
a small-for-gestational-age newborn
congenital cataracts
multiple birth defects
spontaneous abortion

Answer 60

spontaneous abortion

This patient has classic pityriasis rosea. This is generally a benign disease except in pregnancy. The
epidemiology and clinical course suggest an infectious etiology. Pregnant women are more susceptible to
pityriasis rosea because of decreased immunity. Pityriasis rosea is associated with an increased rate of
spontaneous abortion in the first 15 weeks of gestation. It is not associated with an increased risk for a
small-for-gestational-age newborn, congenital cataracts, or multiple birth defects.

Question 61

A 19-year-old college wrestler presents with cellulitis of his left arm extending from a small pustule on his hand to the axilla. He appears acutely ill and has a temperature of 38.9°C (102.0°F). His WBC count is 22,000/mm3 (N 4300–10,800). He is admitted to the hospital.

The initial drug of choice for this patient would be (check one)
ciprofloxacin (Cipro)
clindamycin (Cleocin)
doxycycline
trimethoprim/sulfamethoxazole
vancomycin

Answer 61

vancomycin

Methicillin-resistant Staphylococcus aureus (MRSA) is the predominant cause of suppurative skin and
soft-tissue infection. While community-acquired strains have been susceptible to many antibiotics,
clindamycin is associated with Clostridium difficile enterocolitis, trimethoprim/sulfamethoxazole is usually
used orally only for outpatient treatment, and doxycycline and minocycline are often effective clinically
but seldom used for serious infections. Resistance to quinolones is increasing and may emerge during
treatment. Vancomycin given parenterally is generally still the drug of choice for hospitalized patients.