A Young boy presents with multiple flaccid bullous lesions over trunk with some oral mucosal lesions. Most likely finding on immunofluorescence study of the biopsy specimen would be:
**Core Concept**
The patient's presentation of multiple flaccid bullous lesions over the trunk, along with oral mucosal lesions, suggests an autoimmune blistering disease. Immunofluorescence studies are a crucial diagnostic tool in these cases, helping to identify the underlying pathophysiology.
**Why the Correct Answer is Right**
The correct answer is most likely **Pemphigus vulgaris**, a chronic autoimmune disease characterized by the formation of flaccid bullae due to autoantibodies against desmoglein 3 proteins. These autoantibodies disrupt the intercellular connections between keratinocytes, leading to blister formation. Immunofluorescence studies would show a characteristic "fishnet" or "chicken wire" pattern due to the linear deposition of IgG antibodies along the basement membrane zone.
**Why Each Wrong Option is Incorrect**
**Option B:** This option is incorrect because it is not specific to the clinical presentation of flaccid bullous lesions with oral mucosal involvement.
**Option C:** This option is incorrect because it is a type of bullous pemphigoid, which typically presents with tense bullae, not flaccid ones.
**Clinical Pearl / High-Yield Fact**
In pemphigus vulgaris, the autoantibody response is often triggered by an upper respiratory tract infection, highlighting the importance of a thorough history in diagnosing autoimmune diseases.
**Correct Answer: C. Pemphigus vulgaris**