Background
Subepidermal bullous disorders (SEBD) are a heterogeneous group of vesiculobullous diseases because of antibody‐mediated destruction of proteins of the dermo‐epidermal junction. Direct immunofluorescence (DIF) is the gold standard for diagnosis. BIOCHIP‐indirect immunofluorescence (IIF) is a novel serological test that combines multiple target antigens in a single field. The present study aimed to evaluate the utility of the pattern‐based approach in BIOCHIP‐IIF for the diagnosis of SEBD.
Methods
Seventy cases of BIOCHIP‐IIF that showed clinical, histopathological, and/or DIF features favoring SEBD were included in the study. The interpretation in the BIOCHIP was categorized into one of the following patterns. Pattern I: basement membrane zone (BMZ) staining in monkey esophagus (ME), primate salt‐split skin (SSS)‐roof staining, BP180+ and/or BP230+; Pattern II: roof staining in SSS, BP180– and BP230– with or without BMZ staining in ME; Pattern III: floor staining in SSS, BP180– and BP230–; and pattern IV: negative in SSS and other substrates. The findings were correlated with histopathology and/or DIF.
Results
Fifty (71.5%) cases showed pattern I or the typical bullous pemphigoid (BP) pattern. Eight (11.4%) cases showed pattern II. Patterns III and IV were observed in seven (10%) and five (7.1%) cases, respectively. BP was the most common diagnosis in patterns I and II, while anti‐p200 pemphigoid was most common in pattern III, as confirmed by immunoblotting. The sensitivity of pattern I in the diagnosis of BP was 96%.
Conclusion
BIOCHIP‐IIF showed a good correlation with DIF and histopathology in the diagnosis of SEBD. This can be used as a first‐line investigation in case of bullous disorders.