Aquifer - Dermatology Flashcards
The description of a primary lesion should begin with what 2 features?
Size
Raised or flat
Then describe shape, surface changes, arrangement, overall distribution
Examples of words to describe a lesion by type?
Primary lesion Size Consistency (rubbery, fluctuant, etc.) Color Secondary features (e.g., scaling, crusting, lichenification, excoriation, hypopigmentation
Words to describe arrangement?
Symmetric Scattered Clustered Linear Confluent Discrete
Words to describe location?
Scalp, trunk, extremities, sparing or including palms and soles
Words to describe pattern of distribution
Flexural surfaces Extensor surfaces Sun-exposed skin (photo-distributed) Dependent areas Dermatomal Blaschko-linear
Ways to describe progression over time?
Spreading head to toe or peripheral to central
Changing from papules to vesicles to crusts
Define macule.
Flat, circumscribed discoloration, <1 cm
Define patch.
Larger flat lesion of color change of the skin, >1 cm
Define papule.
Elevated, circumscribed solid lesion, <1 cm
Define plaque.
Broad, elevated lesion (or confluence of papules), >1 cm
Define vesicle.
Circumscribed, elevated lesion containing clear-colored fluid, <1 cm
Define bulla.
Larger, circumscribed, elevated lesion containing clear-colored fluid, >1 cm
Define pustule.
Elevated, exudative lesion (cloudy/yellow/green fluid), variable size
Define nodule.
Circumscribed, elevated lesion that involves the dermis and may extend into the subcutaneous tissue; majority is below the skin
Define wheal.
A blanching, circumscribed, edematous plaque, often with central pallor
May be white to pale red and often appear and disappear over a period of hours
Define telangectasia.
Dilation of superficial venules, arterioles, or capillaries visible on the skin.
Define petechiae.
Tiny, red or purple macules caused by capillary hemorrhage under the skin or mucous membrane that do not blanch
Define purpura.
Larger, purple lesion caused by bleeding under the skin. May be palpable, do not blanch
Define secondary lesions.
Changes that occur later in the course of a lesion or rash
Define scale.
Flakes of keratin that can fine or coarse, loos or adherent
Define crust.
Dried remains of serum, blood, or pus overlying involved skin
Define fissure.
Linear, often painful cleavage in the surface of the skin.
Define erosion.
Slightly depressed lesion in which all or part of the epidermis has been lost. Does not extend into the underlying dermis, so healing occurs without scar formation.
Define ulcer.
Depressed lesion extending into the dermis or subcutaneous tissue, may lead to scar formation
Define excoriation.
Traumatized, superficial loss of the skin, often linear, caused by scratching or rubbing
List the key findings in the diagnosis of an allergic reaction.
- Family history of atopy
- Recurrent rapid onset and resolution of rash (suggesting an acute, repeated response to some type of trigger)
- Pruritis (generally rules out diagnoses such as viral exanthems; likely due to histamine release from mast cells during an allergic inflammation)
- History of a therapeutic response to administration of antihistamine
DDx - Rash (school-age, 5-year-old)
- Roseola
- Papular urticaria
- Streptococcal infection
- Erythema multiforme
- Erythema infectiosum (fifth disease)
- Urticaria due to type 1 hypersensitivity
- Erythema migrans
- Drug eruption
Presentation of roseola?
Common in children <2 years
Viral exanthem for 1-4 days that classically follows 3-5 days of a high fever
As the fever resolves, patients develop a pink, maculopapular rash that starts on the trunk and may spread to the face and extremities
Presentation of papular urticaria?
Pruritic papular lesions 3-10 mm in diameter
Caused by insect bites
Can be recurrent or chronic
Presentation of rash due to streptococcal infection?
Most commonly associated with the rah of scarlet fever, which is a fine, erythematous, sandpaper-like rash accentuated at skin creases
Can also cause an urticarial rash
What is erythema multiforme and how does it present?
Acute hypersensitivity syndrome
Associated with a symmetrical rash that starts as dusky red macules and evolves into sharply demarcated wheals and then into target-like lesions
Individual lesions stay fixed for 1-3 weeks
Does not come and go
Presentation of erythema infectiosum (fifth disease)?
Rash starts on face with a slapped-cheek appearance followed by a reticular (lacy) erythematous rash on the trunk and extremities
Presentation of urticaria due to type 1 hypersensitivity?
Classic lesion: intensely pruritic, circumscribed, raised, erythematous wheal, often with central pallor
Lesions may enlarge and coalesce
Lesions continually change, with new lesions occurring as old ones resolve
Usually asymmetric
Individual lesions tend to last only 12-24 hours
Triggers such as drug, food, insect sting, or infection can sometimes be identified
Presentation of erythema migrans?
Red papule at the site of a tick bite, expands to form a large erythematous annular patch
Presentation of drug eruption?
Commonly urticarial
May be type 1 reaction or may result from non-immunologic triggers of mast cell release (such as from opiates or NSAIDs)
Cause of roseola?
HHV-6
How does the rash in roseola spread across the body?
Starts on the trunk, may spread to the face and extremities
Cause of erythema multiforme?
Most commonly caused by HSV infections, but may be associated with medications
Cause of erythema infectiosum (fifth disease)
Parvovirus B19
How does erythema infectiosum spread across the body?
Starts on face, spreads to trunk and extremities
Cause of erythema migrans?
Localized Lyme disease
Describe the rash typically seen in acute urticaria (hives).
A rash that comes and goes, changing almost as one watches
What often causes hives?
Histamine release triggered by allergens like drugs, foods, or pollen
The underlying cause can include viruses and even temperature
What is the atopic triad?
Atopic dermatitis (eczema), asthma, allergic rhinitis (hayfever)
Diagnosis of acute urticaria?
Blood testing to determine specific allergens or refer to allergist for skin scratch testing
Often difficult to determine a cause, testing should be based on severity and frequency
Treatment of acute urticaria?
Avoid suspected allergens
Symptomatic treatment:
1. OTC antihistamines (loratidine, cetirizine, fexofenadine; related to diphenydramine and hydroxyzine but less sedating)
2. Course of oral prednisone is rarely used if antihistamines don’t control symptoms
3. Keep patient cool and calm (cool, soothing baths -> heat will worsen itching)
DDx - Rash in an Infant
- Seborrheic dermatitis (cradle cap)
- Eczema or atopic dermatitis
- Candidal rash
- Psoriasis
Presentation of seborrheic dermatitis?
Common, consists of erythematous plaques with fine to thick greasy yellow scales
Typically seen on the scalp, but may spread to the ears, neck, and diaper area of infants
Common in infants, unusual to have a new case by age 3
Presentation of eczema or atopic dermatitis on scalp?
May involve the posterior scalp
Positive history of atopy
Pruritic, erythematous, dry, scaling plaques on extensor surfaces on other areas of the body
Presentation of candidal rash in infants?
Commonly manifests as a diaper dermatitis
Characterized by an area of erythema in the inguinal region, as well as erythematous papules and plaques with satellite lesions
Presentation of psoriasis?
Erythematous papules and plaques with a thick, non-waxy silver scale, defined borders
+/- pruritic
Can be annular
Family history (present in 40% of patients)
Chronic disease
Rare in young children -> when present, occurs as a generalized rash known as guttate (droplet-shaped) psoriasis, usually precipitated by a strep infection
Cause of psoriasis?
Hyperproliferation of keratinocytes
Cause of seborrheic dermatitis?
Associated with colonization by malassezia species
Treatment of seborrheic dermatitis in infants?
Baby oil and a small brush to remove the scales
Frequent daily shampooing with a gentle baby shampoo or, for more persistent cases, use of a prescription shampoo containing ketoconazole (anti-fungal) or pyrithione zinc. Avoid getting shampoo in the infant’s eyes
Low-potency topical steroid cream (hydrocortisone)
Acne usually starts as ___. What are the two types?
Comedones (singular comedo)
Open comedones (blackheads) Closed comedones (whiteheads)
Discuss the progression of acne after formation of comedones.
Can become inflamed, leading to larger, erythematous lesions (papules and pustules)
Worst cases -> nodulo-cystic acne
DDx - Pustular conditions
- Staph folliculitis/furunculosis
- Acne vulgaris
- Hidradenitis suppurativa
- Rosacea
- Perioral dermatitis
Presentation and distribution of Staph folliculitis/furunculosis?
Can be very similar to nodular or cystic acne, often below waist or in groin area
Causes of acne vulgaris?
Keratinous material and excess sebum (due to androgenic influence) plug the pilosebaceous gland
Increased sebum provides a growth medium for superinfection with Propioniobacterium acnes
Distribution of acne vulgaris?
Areas of the body with the greatest number of sebaceous glands usually affected, including neck, face, chest, upper back, and upper arms
Cause of hidradenitis suppurativa?
Pustular lesions caused by occlusion of the apocrine follicular units instead of the pilosebaceous units
Often superinfected with S. aureus or S. pyogenes
Distribution of hidradenitis suppurativa?
Markedly different from acne
Women: axillae, groin, inframammary regions
Men: perineal and perianal areas
Presentation and distribution of rosacea?
Most common in adults, early form seen in adoelscents is characterized by inflammatory papules and micropustules, and redness
No comedones
Worse with alcohol, spicy food, temperature extremes, and stress
Malar and nasal surfaces
Rx rosacea?
Topical metronidazole and various other medications
Presentation and distribution of perioral dermatitis?
Variant of rosacea also commonly seen in adolescents and treated the same way
Erythema, scaling, and papules/pustules, but no comedones
Perioral is almost always a misnomer - may be seen around the mouth, nose, or eyes
Presentation of pseudofolliculitis?
Papules often seen in the beard area, inflammation is adjacent to hair follicles
What is erythema nodosum?
Hypersensitivity reaction presenting as red, tender, nodular lesions on pretibial surface of the legs
Many possible etiologies
What factors can exacerbate acne lesions?
Make-up (unless non-comedogenic)
Mechanical factors such as manipulation
Occlusion (as with some sports gear)
Overzealous cleaning
Describe the three categories of acne based on the types of lesions present.
- Mild - comedonal acne with perhaps a few papules or pustules mixed in
- Moderate - significant inflammatory lesions with concern for scarrin
- Severe - nodulo-cystic type, with an even higher risk for significant scarring
Rx - mild acne
Very mild cases - start with OTC benzoyl peroxide (available as a gel or skin wash)
Retinoids work by normalizing follicular keratinization and are considered the drugs of choice for comedonal acne
Rx - moderate acne
BPO + topical antibiotic like clindamycin or erythromycin (antibiotics active against P. acnes)
Options for OC include antibiotics such as doxycycline or tetracycline, or OCs (females)
Rx - severe acne
Refer to dermatologist
If all other treatments have failed or have not been tolerated, many will use oral isotretinoin
Carries significant risks, regulated strictly by the federal government
Discuss timing of treatment with retinoids.
Need to be used at night, because they can cause photosensitization and lead to significant sunburn
Also inactivated by oxidation of BPO, so BPO should be applied in the morning
Must be applied to bone-dry skin or will be significantly irritating
Side effects of doxycycline?
Photosensitivity, esophagitis, dental staining in children under age 9
Teratogenicity
Pseudotumor cerebri
Side effects of minocycline?
Neurological side effects like vertigo
Pseudotumor cerebri
Skin pigmentation (blue/gray after multiple doses)
Lupus-like reaction
Mechanism of oral isotretinoin?
Reduces sebum production, P. acnes proliferation, and follicular hyperkeratotis, and has anti-inflammatory effects
Serious adverse effects of oral isotretinoin?
Depression, hypertriglyceridemia, hepatitis, decreased night vision (vitamin A analog), photosensitivity, serious teratogenicity
Cause of chronic nickel contact dermatitis?
Delayed type IV hypersensitivity reaction
Presentation of contact dermatitis?
Presents 24-72 hours from the start of contact
Can occur despite prior tolerance to exposure
Development depends on whether or not the skin barrier is intact or damaged
Often resolves within days to weeks of avoidance
Rx nickel contact dermatitis?
Avoidance of nickel Good emollient (Vaseline) or a quality skin lubricating cream (Aquaphor or Eucerin) during rash healing Medium-potency topical steroid ointment 2x/day for 2 weeks may help
Presentation of acute contact dermatitis and common causes?
Acute reactions tend to have vesicles, edema, and erythema, very pruritic
Poison ivy/oak/sumac, almost anything can cause it
Most common site for impetigo?
Below the nares (can be anywhere)
Most common bacteria cultured from superficial skin infections?
S. aureus and S. pyogenes (GAS)
Rx impetigo?
Mild localized impetigo - topicals such as mupirocin
Watch for invasive complications such as abscess formation
List the 4 potency groups of topical steroids and their corresponding potency class.
- Mild (6 and 7), e.g. hydrocortisone acetate 1% (OTC)
- Intermediate (4 and 5), e.g. triamcinolone acetonide 0.1%
- Potent (2 and 3), betamethasone dipropionate, 0.05%
- Super potent (1), clobetasol propionate, 0.05%
How does use of topical steroids in children differ from use in adults?
Infants will absorb significantly more medication through the skin than adults, occlusive dressing like a diaper will cause increased absorption
Most important side effects of topical steroid use?
Skin atrophy
Telangiectasias
Hypopigmentation
Suppression of hypothalamic-pituitary axis
First-line treatment for head lice (pediculosis capitis)?
1% permethrin lotion (2-3 applications in weekly intervals)
Rx for head lice in areas where resistance has been demonstrated or if treatment was failed?
Benzyl alcohol 5% (>6 months) or malathion 0.5% (>2 years)
Why is lindane 1% no longer used for head lice treatment?
Known neurotoxicity to humans
Non-pharmacologic treatments for head lice?
Rinsing hair with vinegar or using occlusive ointments have not been shown to be effective.
Any treatment should involve combing wet hair with a fine-toothed comb.
Wash bedding, stuffed animals, hats, combs, brushes, etc. in hot water
Sealing unwashable items in an airtight bag is effective
Cause of scabies?
Mite (Sarcoptes scabiei), acquired by significant close physical contact
Presentation of scabies?
Scabies mite causes itching because it burrows into the skin and lays eggs
Most intense time of itching is often at night
Common distribution sites - wrists, ankles, palms, soles, interdigital spaces, axilla, waist, and groin
Most classic lesion: 5-10 mm curvilinear thread-like lesion (infants do not have this on presentation)
Complications of scabies?
Secondary infections (impetigo, cellulitis) Secondary eczematous dermatitis
Definitive dx of scabies
Identification of mites, eggs, eggshell fragments, or fecal pellets via superficial skin samples (examine with mineral oil using a light microscope under low power)
Rx - scabies
2 applications of permethrin 5% cream 1 week apart (alternative - oral ivermectin)
Apply at nigth before bed, wash off in the morning
Adults - neck down
Infants - entire body including hair and behind the ears
Wash all bed linens and clothing
Post-scabetic itch may persist for a fw weeks due to persistent inflammation
Appearance of tinea corporis (ringworm)?
Annular, well-circumscribed, scaly plaque with a raised border and a center that is brown or hypopigmented
Lesions gradually enlarge and may coalesce
May be mildly pruritic or asymptomatic
Dx tinea corporis?
Usually a clinical diagnosis, but a KOH wet-mount examination of skin scrapings can confirm the diagnosis (classic branches and rod-shaped septated hyphae)
Cause of ringworm?
Fungus (Trichophyton, Microsporum, or Epidermophyton)
Presentation of tinea pedis?
Found on the feet (athlete’s foot)
Young adults > children
May look like ringworm or be scaly, with cracks and fissures between the toes
Presentation of tinea versicolor?
Pink, brown, or white lesions depending on the background color of the skin Fine scale Can change color Can be contagious Excess heat and humidity predispose Recurrences are common
Cause of tinea versicolor?
Yeast form of a fungus (Malassezia globosa and other species -> normal skin flora)
Rx - tinea versicolor
Selenium sulfide lotion
Rx - tinea capitis
Systemic therapy with griseofulvin for 6-8 weeks (oral cannot penetrate the deeper hair follicles of the scalp successfully)
Alternatives - terbinafine and itraconazole
What is kerion?
Infalmed, weeping, boggy lesion requiring treatment with oral steroids; significant allergic response seen with tinea capitis
What makes all tinea infections worse?
Misdiagnosis and subsequent treatment with steroid cream
DDx - Ringworm
- Nummular eczema
- Psoriasis
- Pityriasis alba
- Pityriasis rosea
Presentation of nummular eczema?
Coin-shaped lesions on the legs and buttocks
Annular configuration and scaly appearance
Presentation of pityriasis alba?
Patches of hypopigmentation on the face, neck, upper trunk, and proximal extremities
Lesions range from 0.5 to 5 cm in diameter with well-defined, irregular borders and fine scale
Decreased # of active melanocytes and decreased # and size of melanosomes
Associated with sun exposure
Presentation of pityriasis rosea?
Scaly papules and plaques in the hallmark “Christmas tree” distribution on the back and trunk, following the lines of skin cleavage
Lesions may also be found on the upper thighs and in the groin area
Initial lesion (herald patch) is usually the largest scaly plaque with a raised border
Common cause of warts?
HPV
Presentation of molluscum contagiosum?
Small, smooth umbilicated lesions
Rx of warts?
Observation: 2/3 resolve within 2 years
Salicyclic acid (OTC) - useful for most warts, can be used in children; must apply daily and works slowly
Duct tape - uncertain if this works better than placebo, occlusion and irritation of the skin is the theoretical mechanism
Liquid nitrogen - not as effective as salicylic acid, treatment is a lot faster
Cantharidin - causes blistering at the site of the wart, paucity of data documenting effectiveness, no longer FDA approved as a single agent
Candidal antigen therapy - limited evidence
Curettage
Common causes of diaper rash?
- Irritant dermatitis
- Diaper candidiasis
- Bacterial infection (especially caused by perianal GAS)
Most common cause of diaper rash?
Irritant dermatitis
Cause and presentation of irritant dermatitis?
Due to prolonged exposure to moisture, friction, and digestive enzymes (worse with diarrhea)
Presents as irregular areas of erythema with skin maceration on the convex surfaces of the skin, typically spares intertriginous creases
Rx irritant dermatitis diaper rash?
Keep the area as clean and dry as possible, use zinc oxide-containing creams or ointments (provides a barrier to limit contact of urine and feces with the skin, allows the rash underneath to heal)
Presentation of diaper candidiasis?
Erythematous papules that become confluent, bright red plaques, surrounded by more erythematous papules called satellite lesions, often involves skin folds
Rx - diaper candidiasis?
Nystatin (all ages)
Presentation of GAS diaper rash?
Typically involves the perianal area, may be irritable, streaks of blood in diarrhea
Diaper rash as a manifestation of systemic illness?
Acrodermatitis enteropathica (rare inherited form of zinc deficiency) and langerhans cell histiocytosis
What is neonatal acne?
Not true acne - an inflammatory reaction most likely due to Malassezia; commonly causes papules and pustules over the face
What is the itch that rashes?
Eczema (atomic dermatitis) -> cycle of irritation leads to scratching which leads to the rash
Rx eczema?
- Protect skin with excessive lubrication
- Anti-inflammatories in short bursts
- Rx associated skin infections aggressively
- Medications:
- Topical steroids alternating a higher potency for severe flares with a lower potency for minor bouts (OTC hydrocortisone is often inadequate)
- Topical anti-inflammatories like calcineurin inhibitors are second-line (safety concerns with long-term use)
- Antihistamines to help with itch
Define desquamation
Shedding of the outer layer of the skin surface
Management for roseola?
Reassurance
