Extermely pruritic excoriation & papules on buttocks with autoantibodies against epidermal transglutaminase and IgA deposition in dermis on immuno-histological examination of normal perilesional skin. Diagnosis is:
**Core Concept**
The question describes a clinical presentation of an autoimmune skin disorder characterized by autoantibodies against epidermal transglutaminase and IgA deposition in the dermis. This is a classic example of a celiac disease-related dermatosis, specifically dermatitis herpetiformis.
**Why the Correct Answer is Right**
Dermatitis herpetiformis is a chronic blistering skin disorder that is closely associated with celiac disease. The presence of autoantibodies against epidermal transglutaminase (anti-TG2) is a specific marker for celiac disease and dermatitis herpetiformis. The IgA deposition in the dermis on immunohistological examination is also a characteristic feature of this condition. The clinical presentation of extremely pruritic excoriations and papules on the buttocks is consistent with dermatitis herpetiformis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not match the clinical presentation and immunological findings described in the question.
**Option B:** This option is incorrect because it is a different autoimmune skin disorder that typically presents with mucosal involvement and is associated with autoantibodies against desmoglein 3.
**Option C:** This option is incorrect because it is a different skin condition that presents with blistering and is associated with autoantibodies against type II collagen.
**Clinical Pearl / High-Yield Fact**
Dermatitis herpetiformis is often associated with celiac disease, and patients with this condition may benefit from a gluten-free diet. It is essential to consider this diagnosis in patients with a history of celiac disease or gluten sensitivity who present with skin lesions.
**Correct Answer:** D. Dermatitis herpetiformis.