Physician Assistant Exam: Eczema and Dermatitis
Eczema and dermatitis refer to anything that causes skin inflammation, and the causes are covered on the Physician Assistant Exam (PANCE). Dermatitis is a nonspecific term that refers to skin inflammation. Eczema, a type of dermatitis, has some characteristic skin findings — the skin can be flaky, itchy, scaly, and red. Sometimes scratching can make it redder. Unfortunately, there’s no magic cure.
The gold standard of treatment is searching for the underlying cause and using topical steroids or antipruritic agents (desoximetasone, sold as Topicort Emollient Cream) as needed. Questions you’re likely to ask someone who has eczema are along the lines of “Any new allergies?” (for allergy-mediated or atopic eczema) and “Any new shampoos or new detergents you haven’t used before?” (for a contact type of dermatitis).
For the purposes of the PANCE, be familiar with two types of eczema:
Dyshidrosis: In this type of dermatitis, skin lesions occur on the palmar surface of the hands and the plantar aspect of the feet. You see these scaly lesions along the digits as well.
Lichen simplex chronicus: If you scratch an eczematous lesion long enough and often enough, you can cause changes consistent with lichen simplex chronicus (LSC, also known as neurodermatitis). The underlying pathology is somewhat of a mystery. Is there an inflammatory component? An allergic component? How about both?
You see lichen simplex chronicus a little more commonly in people with contact dermatitis. A hallmark of lichen simplex chronicus is the “itchy fits,” episodes of intense itching. The treatment of this is topical steroids. If the person scratches so much that the skin becomes infected, then you may need to prescribe a topical antibiotic.
You’re examining a 35-year-old woman who presents with a scaly, eczematous rash on her elbows and thighs. She was just told she has an intolerance to gluten. Which one of the following conditions are you likely dealing with?
(B) Lyme disease
(C) Acne vulgaris
(D) Dermatitis herpetiformis
The correct answer is Choice (D), dermatitis herpetiformis. Given the popularity and prevalence of celiac disease (gluten sensitivity-mediated disease), you should be familiar with the close association between celiac disease and dermatitis herpetiformis, a type of eczema. Choice (A), dyshidrosis, is a type of eczema with a different distribution; if dyshidrosis were the answer, the question would mention “pruritic, deep-seated, tapioca-like vesicles.”
Choice (B), Lyme disease, is characterized by the bull’s-eye rash (erythema migrans). Choice (C), acne vulgaris, is the typical acne you fretted over as a teenager. It has a predilection for the facial area and is associated with Propionibacterium acnes. Choice (E), cellulitis, is a maculopapular erythematous lesion on the lower extremities. It’s caused by a bacterial infection, usually a Staph or Strep species.