32 Flashcards
Key findings in the dx of an allergic rxn 4
The following findings in a patient’s history would point toward 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 (Pruritis is a helpful clinical feature as it generally rules out diagnoses such as viral exanthems. The pruritis is likely due to histamine release from mast cells during an allergic inflammation.)
History of a therapeutic response to administration of antihistamine is also a helpful finding.
Diff dx of rash in toddler (5 years old) 8
Urticaria due to type 1 hypersensitivity
Classic lesion is an intensely pruritic, circumscribed, raised, erythematous wheal, often with central pallor.
The pruritis is due to histamine release from mast cells.
Individual lesions may enlarge and coalesce with other lesions.
The lesions continually change, with new lesions occurring as old ones resolve.
Usually asymmetric.
Acute urticaria (due to type 1 hypersensitivity) affects up to 15% of the population at some point in their lives.
Individual lesions tend to last only 12–24 hours.
A trigger such as a drug, food ingestion, insect sting, or infection can sometimes be identified.
Papular urticaria
Common pediatric condition.
Lesions are papular and 3 mm to 10 mm in diameter.
Caused by insect bites.
Can be recurrent or chronic.
Pruritic.
Streptococcal infection
Most commonly associated with the rash of scarlet fever, which is a fine, erythematous, sandpaper-like rash accentuated at skin creases.
Also known to cause an urticarial rash.
Erythema multiforme
An acute hypersensitivity syndrome
Associated with a symmetrical rash that starts as a dusky red macules and evolves into sharply demarcated wheals and then into target-like lesions - red around edges but central pallor
Individual lesions stay fixed for one to three weeks.
Condition does not come and go.
Most commonly caused by herpes simplex infections, but may be associated with medications.
Drug eruption
Commonly urticarial.
May be Type 1 hypersensitivity reactions or may result from non-immunologic triggers of mast cell release (such as from opiates or NSAIDs).
Roseola
A viral exanthem that classically follows 3-5 days of a febrile illness.
As the fever resolves, patients develop a pink, maculopapular rash that starts on the trunk and may spread to the face and extremities.
Caused by human herpes virus-6 (HHV-6).
Erythema infectiosum (Fifth disease)
Rash starts on the face with a “slapped”-cheek appearance followed by a reticular (lacy) erythematous rash on the trunk and extremities.
Caused by parvovirus B19.
Erythema migrans
Lesion associated with early localized Lyme disease -target lesion
Starts as a red papule at the site of a tick bite.
Expands to form a large erythematous, annular patch.
Acute urticaria (hives)
Fam Hx
Dx
Tx
A rash that comes and goes—changing almost as one watches—is very consistent with acute urticaria, also known as hives.
Often hives are caused by a histamine release triggered by allergens like drugs, foods, or pollen. The underlying cause can include viruses and even temperature. The offending trigger or agent can’t always be determined.
Atopic History
A family history including any or all of the following conditions called the atopic triad:
atopic dermatitis (eczema)
asthma
allergic rhinitis (hayfever)
Diagnosis
Blood testing to determine specific allergens can be done in the office, or patient can be referred to an allergist for skin scratch testing. It is often difficult to determine a cause, and testing should be based on severity and frequency.
Treatment
- Avoid suspected allergens
- Symptomatic treatment:
Over-the-counter antihistamines (e.g., hydroxyzine, loratidine or cetirizine; these are related to diphenydramine [Benadryl] but are less sedating).
A course of oral prednisone is rarely used if antihistamines don’t control the symptoms. (Topical steroids don’t seem to be as effective, especially since hives can occur all over the body, be transient, and cover large areas.)
Keep patient cool and calm (try cool, soothing baths; heat will worsen the itching).
Diff dx of rash in an infant (3 months) 4
Seborrheic dermatitis (cradle cap)
Seborrheic dermatitis is common.
Consists of erythematous plaques with fine to thick, greasy yellow scale.
Typically seen on the scalp, but may spread to the ears, neck, and diaper area of infants.
Eczema or atopic dermatitis
May involve the posterior scalp.
A positive history of atopic diathesis would support this diagnosis.
Look for pruritic, erythematous, scaling plaques on extensor surfaces as evidence of atopic dermatitis on other areas of the body.
Candidal rash
Commonly manifests as a diaper dermatitis peaking between 7-10 months of age.
Characterized by an area of erythema in the inguinal region, as well as erythematous papules and plaques with satellite lesions.
Psoriasis
More erythematous, with a thicker, non-waxy scale and more defined borders than seborrheic dermatitis.
May or may not be pruritic.
A family history of psoriasis is present in 40% of patients.
Seborrheic dermatitis tx
Seborrheic dermatitis is a very common skin condition for many infants. There is little or no harm in this condition, and most children grow out of it whether it is treated or not.
In older patients it is often caused by a fungus (Malassezia).
Treatment
For infants, treatment can include:
Baby oil and a small brush to remove the scales
Frequent (i.e., daily) shampooing with a gentle baby shampoo, or - for more persistent cases - use of a prescription shampoo containing ketoconazole, an anti-fungal agent, or pyrithione zinc. Care must be taken not to get the shampoo in the infant’s eyes.
A low-potency topical steroid cream (e.g., hydrocortisone). In older children and adults, ketoconazole cream may be used.
Diff dx for pustular conditions 5
Often below waist or in groin area.
Acne vulgaris
Due to several processes:
Keratinous material and excess sebum (due to androgenic influence) plug the pilosebaceous gland.
Increased sebum provides a growth medium for superinfection with Propioniobacterium acnes.
Areas of the body with the greatest number of sebaceous glands usually affected, including:
Neck
Face
Chest
Upper back
Upper arms
Hidradenitis suppurativa
Pustular lesions caused by occlusion of the apocrine follicular units (instead of the pilosebaceous units).
Often superinfected with Staphylococcus aureus or Streptococcus pyogenes.
Distribution markedly different from acne. Areas most likely affected in women:
Axillae
Groin
Inframammary regions
In men:
Perineal and perianal areas more commonly affected.
Rosacea
More often seen in adults.
“Early” form seen in adolescents is characterized by inflammatory papules and micropustules, and redness.
No comedones.
Worsens with alcohol, spicy food, temperature extremes, and stress.
Can be treated with topical metronidazole and various other medications.
Malar and nasal surfaces.
Perioral dermatitis
A variant of rosacea also commonly seen in adolescents, and treated the same way.
See erythema, scaling, and papules or pustules, but no comedones.
“Perioral” almost a misnomer, as this may be seen around the mouth, nose, or eyes.
Acne triggers 4
The following are known to exacerbate acne lesions:
Make-up (unless noncomedogenic)
Mechanical factors such as manipulation)
Occlusion, as occurs with some sports gear
Overzealous cleaning
There is an unsubstantiated link with high-glycemic diets and acne. High-quality controlled studies are needed.
Uncleanliness does not worsen acne
3 categories of acne and its treatment
When deciding on a treatment, it is important to take into consideration how much the acne affects the person’s quality of life.
Acne is divided into three categories based on the type(s) of lesions present:
Mild Comedonal acne with perhaps a few papules or pustules mixed in
Moderate Significant inflammatory lesions with concern for scarring
Severe Nodulo-cystic type, with an even higher risk for significant scarring
Type Treatment Considerations
Mild
For very mild cases, many physicians use OTC benzoyl peroxide (BPO) as a good starting point. (However, if a patient is coming to see a physician about acne, he or she usually needs something stronger.)
BPO is available as a gel or as a skin wash.
Retinoids (e.g., tretinoin [Retin-A] or adapalene [Differin]) work by normalizing follicular keratinization and are considered the drugs of choice for comedonal acne.
Moderate
For anything other than mild acne, the same initial treatments should be used with the addition of another product. (This management strategy should be familiar to you, as pediatricians often use step-wise evaluation and management plans.)
Antibiotics can be an important adjunct in the treatment of acne.
BPO can be combined with a topical antibiotic like clindamycin or erythromycin (antibiotics active against P. acnes), each agent addressing a different cause for the acne.
Topical prescription products exist in combination form or may be used in combination.
Options for oral therapy include antibiotics such as doxycycline or tetracycline, or contraceptive pills (for females).
Severe
Patients with severe acne should be referred to a dermatologist.
If all other treatments have failed or have not been tolerated, many dermatologists will then use oral isotretinoin.
This medication carries significant risks and it is regulated very strictly by the federal government.
A Note About Timing
Timing of treatment with retinoids is important:
Retinoids need to be used at night, because they can cause photosensitization and lead to a significant sunburn.
Tretinoin is also inactivated by oxidation of BPO (so the BPO cream should be applied in the morning).
Tretinoin also must be applied to bone-dry skin or it may be significantly irritating.
It is important to make sure teens know that retinoids can make acne transiently look worse.
Chronic nickel contact dermatitis and its tx
This fairly common skin condition (view photo) is an example of a delayed type IV hypersensitivity reaction.
The reaction requires sensitization, so onset is usually within 24-72 hours from the start of contact.
These reactions can occur despite prior tolerance to exposure.
Development of a rash depends on whether or not the skin barrier is intact or damaged.
The rash often resolves within days to weeks of avoidance.
If the allergy is difficult to control, some will refer to an allergist to consider “patch testing” to evaluate for nickel or other allergen leading to allergic contact dermatitis.
Treatment
Avoidance of nickel, which can be found in many buttons and jewelry.
While the rash is healing, apply a good emollient (such as petroleum jelly [Vaseline]) or a quality skin lubricating cream [such as Aquaphor or Eucerin]).
A medium-potency topical steroid ointment (twice a day for two weeks) may also be used to help the rash to resolve.
weepy” and honey-colored crusts lesion
The most common site for impetigo is right below the nares (because of rubbing and colonization), but it can be anywhere on the body.
Infectious Organism
The most common bacteria cultured from superficial skin infections are Staphylococcus aureus and Streptococcus pyogenes (Group A Strep).
Treatment
Mild localized impetigo can be treated effectively with topical antibiotics such as mupirocin.
However, due to the widespread emergence of methicillin-resistant staphylococcus aureus (MRSA), clinicians must be vigilant to watch for invasive complications such as abscess formation.
This and other potential complications merit more aggressive therapy and systemic antibiotics.
Topical steroids
Physicians in every field need to understand the appropriate and judicious use of topical corticosteroids. Topical steroids are a powerful and effective treatment for many dermatologic conditions; however, there are important side effects and adverse reactions to be considered.
Potency
The most important thing to know prior to prescribing a topical steroid is its potency. There are various ways to classify potency. It is common to use four potency groups, which correspond to seven potency classes. Here’s a table that breaks that down:
Potency Group Potency Class Example
Mild Class 6 & 7 hydrocortisone acetate, 1% (OTC)
Intermediate Class 4 & 5 triamcinolone acetonide, 0.1%
Potent Class 2 & 3 betamethasonedipropionate, 0.05%
Super Potent Class 1 clobetasol propionate, 0.05%
The class 1 agent clobetasol, 0.05%, is approximately 1000 times more potent than over-the-counter hydrocortisone,1%
Vehicle
Disease etiology usually dictates whether an ointment or cream is used; eczema, for example, should be treated with ointments, which offer more effective skin penetration. The base is not as important in psoriasis, however, and it may be treated with ointment or cream, depending on patient preference.
Chemical Formulation
The chemical formulation matters, too:
As an example, hydrocortisone valerate is much more potent than hydrocortisone acetate.
Use of Steroids in Children
When prescribing steroids to children it is important to keep in mind that infants will absorb significantly more medication through their skin than adults and that an occlusive dressing (like a diaper!) will cause increased absorption.
Side Effects
There are many potential side effects of topical steroid use. The most important are:
Skin atrophy
Telangiectasias
Hypopigmentation
Suppression of the hypothalamic-pituitary axis
Even low-potency topical steroids can cause these problems when used for long durations or over large areas of the body. Particular caution should be used when considering the use of steroids on the face or genitalia.
Treatment of head lice (pediculosis capitis)
Pharmacological Treatments
Currently, the first-line treatment is 1% permethrin lotion, available in the U.S. without a prescription. Permethrin has very low toxicity, but may require two or three repeated applications in weekly intervals to achieve full effect. Pediatric providers should be aware of local resistance patterns
Benzyl alcohol 5% (for children older than 6 months) or malathion 0.5% (for children 2 years old or older) can be used in areas where resistance to permethrin or pyrethrins has been demonstrated or for a patient with a documented infestation that has failed to respond to appropriately administered therapy with permethrin or pyrethrins.
Lindane 1%, formerly the treatment of choice, is no longer recommended for use because of known neurotoxicity to humans. In addition, there is widespread resistance.
Non-Pharmacological Treatments
Many parents try methods such as rinsing hair with vinegar or using occlusive ointments to “suffocate” the lice; neither has been shown to be effective in high quality trials. Occlusive treatments in combination with wet combing is an option in areas of high resistance.
While not perfect at removing nits, any treatment should involve combing the wet hair with a fine-toothed comb.
Bedding, stuffed animals, hats, combs and brushes, and other contaminated items should be washed in hot water or dried in high heat in the dryer.
Sealing unwashable items in an airtight bag also is effective, as the lice cannot live away from a host for more than 26 hours, and the newly born nymphs must feed immediately if they are to survive.
Scabies: Presentation Complications Dx Tx
Scabies is a very common skin infestation. Like lice, it has nothing to do with cleanliness. It is caused by a mite (a small insect), Sarcoptes scabiei, and is acquired by significant close physical contact.
Presentation
The scabies mite causes itching because it burrows into the skin and lays eggs.
The most intense time of itching is often at night.
Wrists, elbows, fingers, and toes are among the common distribution sites for scabies.
The most classic lesion for scabies is about a 5-10 mm curvilinear thread-like lesion–the burrow; but infants often do not have burrows on presentation.
Complications
There can be secondary infections, including impetigo or even cellulitis.
Often a secondary eczematous dermatitis may also be involved.
If the underlying cause is not identified and treated, the patient’s suffering will continue.
Diagnosis
Scabies is often very difficult to diagnose in infants, because of its atypical appearance.
In these cases, talking with other family members is very important.
Definitive diagnosis relies on the identification of mites, eggs, eggshell fragments, or fecal pellets: Multiple superficial skin samples should be obtained from characteristic lesions—specifically, burrows or papules and vesicles in the site of burrows—by scraping laterally across the skin with a blade; specimens can then be examined with mineral oil using a light microscope under low power.
Treatment
Treatment is with two applications of permethrin 5% cream, one week apart, for all affected household members.
The cream is applied at night before bed and washed off in the morning, or after around 8-12 hours.
Adults should apply the cream from the neck down.
For infants, the entire body should be covered from the hairline down, including behind the ears, being careful to avoid the areas around the eyes and mouth.
After bathing, wash all bed linens and clothing worn during treatment.
Itching (known as “post-scabetic itch”) may persist for a few weeks after the mites have been killed and is due to persistent inflammation from the infestation. A moderate potency topical steroid and over-the-counter diphenhydramine may be helpful.
Sometimes families need to be re-treated or discover there was another hidden exposure.
Alternative Treatment
If there is an allergic response to permethrin—or if it does not work—oral ivermectin is often effective, although currently not approved by the FDA for children under 15 kg.
Ringworm: appearance and dx
Appearance
The classic lesion of ringworm of the body (tinea corporis) is an annular, well-circumscribed, scaly plaque with a raised border and a center that is brown or hypopigmented.
Lesions gradually enlarge and may coalesce with surrounding lesions.
Lesions may be mildly pruritic or asymptomatic.
Diagnosis
Can usually be diagnosed clinically, but a KOH wet-mount examination of skin scrapings can confirm the diagnosis. (Obtain a scraping with the edge of a glass slide or a #15 blade and examine it under low power with the microscope light dimmed to see the classic branches and rod-shaped septated hyphae.)
Differential for ringworm 4
Nummular eczema
Consists of coin-shaped lesions commonly on the legs and buttocks.
Has an annular configuration and scaly appearance like tinea.
Psoriasis
Commonly presents with erythematous papules and plaques with a thick silver scale.
May also have an annular configuration that could be mistaken for tinea.
A chronic disease.
Pityriasis alba
A nonspecific dermatitis characterized by 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.
Aassociated with sun exposure.
May be mistaken for tinea versicolor.
Pityriasis rosea
Characterized by 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.
The initial lesion, called the “herald patch,” is usually the largest scaly plaque with a raised border and can easily be confused with tinea corporis.
