Question

A 30 year old woman came with flaccid bullae on her skin which were easy to rupture. Biopsy of the lesion revealed a suprabasal split. What is the most likely diagnosis?

• A. Pemphigus vegetans
• B. Pemphigus vulgaris
• C. Pemphigus foliaceous
• D. Erythema multiforme

Hint:

The level of the epidermal split on biopsy is the key to diagnosing pemphigus subtypes.

Answer 1

The Correct Option is B

Step 1: Identify the key histological finding.
The biopsy shows a suprabasal split -- this means the cleavage (separation) occurs just above the basal layer of the epidermis. This is the hallmark of pemphigus vulgaris.

Step 2: Understand the pathophysiology.
Pemphigus vulgaris is an autoimmune blistering disorder caused by IgG antibodies directed against desmoglein 3 (and sometimes desmoglein 1). These desmogleins are transmembrane glycoproteins responsible for keratinocyte adhesion (desmosomes). Loss of this adhesion leads to acantholysis (separation of epidermal cells) and blister formation just above the basal layer (suprabasal acantholysis).

Step 3: Identify the clinical features.
- Flaccid bullae (thin-roofed, easy to rupture)
- Nikolsky sign positive (lateral pressure on skin causes blister extension)
- Oral mucosa commonly involved
- Basal cells remain attached to basement membrane (tombstone pattern on histology)
- Acantholytic cells (Tzanck cells) seen in blister fluid

Step 4: Differentiate from other options.
- Pemphigus vegetans: variant of pemphigus vulgaris with vegetating plaques, also suprabasal -- but the clinical description here is classic for pemphigus vulgaris.
- Pemphigus foliaceous: subcorneal split (superficial cleavage), caused by anti-desmoglein 1 antibodies; does not involve mucous membranes.
- Erythema multiforme: subepidermal blistering with keratinocyte necrosis, target lesions on skin; not suprabasal.