Pemphigus vulgaris is an autoimmune blistering disorder caused by antibodies against desmoglein 3 and desmoglein 1
Immunofluorescence is essential for its diagnosis.
Direct immunofluorescence (DIF), the gold standard, is performed on perilesional tissue and shows intercellular space (ICS) deposition of IgG, often accompanied by C3, throughout the epithelium. This produces the classic “fish-net” or “chicken wire” pattern, reflecting antibody binding between keratinocytes. A similar intercellular pattern is also seen in pemphigus foliaceus.
Indirect immunofluorescence (IIF) detects circulating antibodies in patient serum and may correlate with disease activity.
The intercellular fluorescence pattern helps differentiate pemphigus from pemphigoid, where staining is seen along the basement membrane.
A lesser-known but clinically valuable point is that even in cases where the epidermis is lost (e.g., in ulcerated or improperly biopsied tissue), direct immunofluorescence may still demonstrate
intercellular or linear staining in adnexal structures such as sweat glands and hair follicles. This can serve as an important diagnostic clue for pemphigus vulgaris.
Thus, immunofluorescence not only confirms diagnosis but also provides insight into disease distribution and subtle diagnostic scenarios.
MBH/AB