Analysis of the utility of direct immunofluorescence in the diagnosis of common immune mediated dermatological conditions

Abstract

Background: Accurate diagnosis of immune-mediated dermatological diseases requires an evaluation of clinical, histopathological, and immunofluorescence findings. Immunofluorescence detects antibodies bound to antigens in tissue and in circulating body fluids. It acts as a valuable adjunct to clinical and histopathological diagnosis in patients of autoimmune bullous diseases (AIBDs), connective tissue diseases (CTD), and vasculitis. Aim: This study aimed to analyze the utility of direct immunofluorescence (DIF) in the diagnosis of common immune-mediated dermatological diseases by its correlation with clinical features and histopathology. Methodology: This is an observational retrospective study. Medical records of 205 clinically suspected patients of AIBD, CTD, and vasculitis were retrieved for analysis where both histopathology and DIF had been carried out for patients treated at the dermatology department of a tertiary care hospital between November 2015 and November 2018. Data were analyzed using Statistical Package for the Social Sciences software version 20.0. Results: A total of 187 out of 205 patients were accurately diagnosed based on histopathology and DIF studies. Histopathology was positive in 177/187 (95.7%) patients and DIF was positive in 153 (81.8%) patients. Clinical, histopathological, and DIF discordance was seen in the remaining 18 out of 205 patients. The sensitivity of DIF in AIBD, lupus erythematosus (LE), and vasculitis was calculated to be 89%, 82.6%, and 60%, respectively. The overall sensitivity of DIF was 80.8%. The sensitivity of DIF was 100% in pemphigus foliaceous, acute cutaneous lupus erythematosus, and immunoglobulin A (IgA) vasculitis. Out of 118 clinically suspected AIBD patients, nine were diagnosed on the basis of DIF alone. Conclusion: DIF is an indispensable tool in the accurate diagnosis of autoimmune dermatological conditions, especially in cases where clinical and/or histopathological features are inconclusive. It is invaluable in confirming the diagnosis of IgA vasculitis.