Which of the following shows deposition of IgA in dennal papilla –
**Core Concept**
The question is testing the concept of immunofluorescence patterns in autoimmune diseases, specifically the deposition of immunoglobulins (IgA) in skin diseases. The correct answer requires knowledge of the characteristic immunopathological findings in IgA dermatosis.
**Why the Correct Answer is Right**
IgA dermatosis, also known as linear IgA bullous dermatosis, is a rare autoimmune skin disease characterized by the deposition of IgA antibodies along the basement membrane zone (BMZ). The disease typically presents with subepidermal blisters and linear band of IgA deposition on direct immunofluorescence (DIF) of skin biopsy specimens. The deposition of IgA is thought to be due to the activation of plasma cells and the production of autoantibodies against the BMZ components.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because IgA dermatosis primarily involves IgA antibodies, not IgG or IgM.
* **Option B:** This option is incorrect because pemphigus vulgaris is characterized by IgG deposition, not IgA.
* **Option C:** This option is incorrect because bullous pemphigoid typically involves IgG and C3 complement deposition, not IgA.
**Clinical Pearl / High-Yield Fact**
For exam purposes, remember the "3 Ps" of autoimmune blistering diseases: pemphigus (IgG), pemphigoid (IgG+C3), and IgA dermatosis (IgA).
**Correct Answer:** C.