Diagnostic Efficacy of Clinical Diagnosis, Histopathological Diagnosis as Compared to Direct Immunofluorescence in Autoimmune Blistering Diseases - A Study from South Kerala

BACKGROUND Autoimmune blistering diseases contribute to a significant number of patients attending the dermatology department. As they have a varied presentation, definite clinical diagnosis is not possible always. Histopathology is also inconclusive sometimes. Immunofluorescence studies are now considered to be most valid in diagnosing these problems. Direct immunofluorescence study of perilesional skin will help us to identify the type of immunoreactants and their exact site of location. This may help dermatologist to make accurate and prompt diagnosis. Hence we decided to conduct this study. METHODS We conducted a diagnostic tool evaluation cross sectional study in 34 patients, who attended dermatology outpatient department (OPD) of a major tertiary care centre in South Kerala, with a clinical diagnosis of immunobullous disease. We performed histopathology and direct immunofluorescence (DIF) in all our patients. RESULTS Age group of study population ranged from 31 – 90 years with a definite female preponderance. 32.4 % of our patients had intraepidermal immunobullous diseases while rest had subepidermal disorders. Pemphigus vulgaris was the commonest intraepidermal disease reported, with most patients presenting in fifth and sixth decade. Oral erosions were the presenting symptom in 97.5 % patients. Classical histopathology was seen in all except one, clinicopathological correlation being 87.5 %. Pemphigus erythematosus could be diagnosed only by DIF. Direct immunofluorescence had 100 % negative predictive value (NPV). Among subepidermal immunobullous diseases, bullous pemphigoid was seen in 19 patients with age ranging from 41 - 90 years. Clinical, histopathological and DIF correlation in bullous pemphigoid was 100 %. Clinical diagnosis of lichen planus pemphigoids and bullous systemic lupus erythematosus could be confirmed by histopathology and DIF while linear IgA disease showed features of bullous pemphigoid in DIF. Positive and negative predictive value reached 100 % in the present study. CONCLUSIONS Direct immunofluorescence study is a useful investigation for the correct diagnosis of various immunobullous diseases although histopathology is more relevant in diagnosis of certain subtypes of pemphigus. KEY WORDS Immunobullous Diseases, Direct Immunofluorescence, Histopathology.