**Question:** A middle aged female has flaccid bullae in the skin and oral erosion. Histopathology shows intraepidermal acanthololytic blisters. The most likely diagnosis is –

A. Pemphigus vulgaris
B. Pemphigus foliaceus
C. Eosinophilic folliculitis
D. Sweet syndrome

**Correct Answer:** B. Pemphigus foliaceus

**Core Concept:**
Pemphigus is a group of autoimmune diseases characterized by blistering of the skin and mucous membranes. In pemphigus, autoantibodies target desmoglein proteins, which are desmosomal cadherins involved in the maintenance of epidermal integrity.

**Why the Correct Answer is Right:**
In this scenario, the patient presents with intraepidermal acanthololytic blisters, which are consistent with pemphigus foliaceus. Pemphigus foliaceus is a subtype of pemphigus characterized by autoantibodies targeting desmoglein 1 (DSG1), a key component of desmosomes in the epidermis. This autoimmune response leads to intraepidermal blistering, as seen in the patient's histopathology.

**Why Each Wrong Option is Incorrect:**
A. Pemphigus vulgaris: This subtype is characterized by autoantibodies targeting desmoglein 3 (DSG3), which is involved in bullous pemphigoid rather than pemphigus.
C. Eosinophilic folliculitis: This is a distinct entity characterized by eosinophilic infiltration and neutrophilic abscess formation, not intraepidermal blistering.
D. Sweet syndrome: Sweet syndrome is a neutrophilic dermatosis associated with fever, elevated inflammatory markers, and neutrophilia, which is not present in Pemphigus foliaceus.

**Clinical Pearl:** Histopathological examination of skin biopsies plays a crucial role in differentiating various blistering disorders, including pemphigus and pemphigus foliaceus. This helps in initiating appropriate management, including immunosuppressive therapy, which can prevent potential complications and severe disease manifestations.