A 35-year-old man has had an outbreak of pruritic lesions over the extensor surfaces of the elbows and knees during the past month. He has a history of malabsorption that requires him to eat a special diet, but he has had no previous skin problems. On physical examination, the lesions are 0.4- to 0.7-cm vesicles. A 3-mm punch biopsy of one of the lesions over the elbow is performed and on microscopic examination shows the accumulation of neutrophils at the tips of dermal papillae and the formation of small blisters caused by separation at the dermo-epidermal junction. Immunofluorescence studies show granular deposits of IgA localized to tips of dermal papillae. Laboratory studies show serum antigliadin antibodies. What is the most likely diagnosis?
A 35-year-old man has had an outbreak of pruritic lesions over the extensor surfaces of the elbows and knees during the past month. He has a history of malabsorption that requires him to eat a special diet, but he has had no previous skin problems. On physical examination, the lesions are 0.4- to 0.7-cm vesicles. A 3-mm punch biopsy of one of the lesions over the elbow is performed and on microscopic examination shows the accumulation of neutrophils at the tips of dermal papillae and the formation of small blisters caused by separation at the dermo-epidermal junction. Immunofluorescence studies show granular deposits of IgA localized to tips of dermal papillae. Laboratory studies show serum antigliadin antibodies. What is the most likely diagnosis?
💡 Explanation
**Core Concept**
The patient's symptoms are indicative of a dermatological condition characterized by the deposition of IgA antibodies at the dermo-epidermal junction, leading to the formation of vesicles on extensor surfaces. This condition is associated with autoimmune reactions and is linked to malabsorption and the presence of specific autoantibodies.
**Why the Correct Answer is Right**
The clinical presentation and laboratory findings are consistent with dermatitis herpetiformis, a chronic skin condition characterized by the deposition of IgA antibodies at the tips of dermal papillae. This leads to the formation of small blisters and vesicles on extensor surfaces, such as the elbows and knees. The presence of granular deposits of IgA as seen on immunofluorescence studies is a hallmark of this condition. The association with malabsorption and the presence of serum antigliadin antibodies further supports this diagnosis.
**Why Each Wrong Option is Incorrect**
**Option A:** Bullous pemphigoid is a separate autoimmune blistering disorder characterized by the deposition of IgG and C3 at the basement membrane zone, not IgA at the tips of dermal papillae.
**Option B:** Pemphigus vulgaris is an autoimmune blistering disorder characterized by the deposition of IgG antibodies against desmoglein 3, leading to intraepidermal blistering, not IgA deposition at the dermo-epidermal junction.
**Option C:** Eczema herpeticum is a complication of atopic dermatitis characterized by the superinfection of vesicles with herpes simplex virus, not a primary autoimmune condition.
**Option D:** Contact dermatitis is a type of skin inflammation caused by exposure to allergens or irritants, not an autoimmune condition characterized by IgA deposition at the dermo-epidermal junction.
**Clinical Pearl / High-Yield Fact**
Dermatitis herpetiformis is a skin manifestation of celiac disease and is associated with the presence of serum antigliadin antibodies. The condition can be managed with a strict gluten-free diet.
**Correct Answer:** D. Dermatitis herpetiformis.
✓ Correct Answer: C. Dermatitis herpetiformis
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