Review Question - QID 104237

This patient's presentation is consistent with dermatitis herpetiformis, a dermatologic manifestation of celiac disease.

Dermatitis herpetiformis is a pruritic rash of extensor surfaces that occurs due to IgA deposition in the dermis. It is treated with dapsone, and response to dapsone confirms the diagnosis of the condition. Response typically occurs within hours. GI symptoms in patients with dermatitis herpetiformis and celiac disease are often absent, but the lesions respond to a gluten-free diet.

Bickle et al. describe dermatitis herpetiformis as pruritic, chronic, and characterized by papulovesicles and urticarial wheals. It occurs on the extensor surfaces in a grouped (herpetiform) symmetric distribution. Linear IgA dermatosis is a clinically similar entity that is not associated with intolerance to gluten.

Nakajima explains that IgA and antibodies against epidermal transglutaminase-3 play an important role in the pathogenesis of dermatitis herpetiformis.

Illustration A shows the typical pruritic rash of dermatitis herpetiformis. Illustration B shows the rash of leprosy for comparison. Both are treated with dapsone. Illustration C shows endoscopic and histologic images comparing normal intestine with gut mucosa in celiac disease. Note the villous atrophy, crypt lengthening, and increased epithelial lymphocytes in celiac disease.

Incorrect Answers:
Answer 1: Candida intertrigo appears within the folds of the skin.
Answer 2: Porphyria cutanea tarda is not treated with dapsone. It does not feature abdominal pain such as is seen in the other porphyrias.
Answer 3: Systemic lupus erythematosus is not treated with dapsone.
Answer 5: Leprosy, caused by Mycobacterium leprae infection, is also treated with dapsone. However, leprosy has a systemic presentation, including leonine facies and motor and sensory loss in lepromatous leprosy. Recall that lepromatous leprosy develops when the immune response fails while tuberculoid leprosy develops when the immune response is intact.