Spectrum of autoimmune bullous diseases seen at Chris Hani Baragwanath Academic Hospital and Charlotte Maxeke Johannesburg Academic Hospital, South Africa

Abstract

Background Autoimmune bullous diseases (AIBDs) are potentially life-threatening blistering dermatoses in which autoantibodies target skin and mucous membranes. Epidemiologic data about AIBD subtypes are limited. We described the number of new cases of AIBDs at two academic hospitals in Johannesburg, South Africa, by demographics, AIBD subtype and year of diagnosis. Methods We conducted a retrospective observational study of histopathology records from the laboratory database and patient demographic information from the hospital database. Eligible records included new diagnoses of AIBD confirmed between 2013 and 2021 by histology and direct immunofluorescence with or without salt-split skin testing. We collected data on demographics (age at diagnosis, sex and race), AIBD subtype and year of diagnosis. Descriptive statistics were calculated. Results Over nine years, 169 people were newly diagnosed with AIBD, with a median age of 65 years. Most were female (66.9%) and Black African (91.1%). The commonest AIBD subtypes were bullous pemphigoid (68%), pemphigus foliaceous (9.5%), pemphigus vulgaris (7.7%) and linear IgA bullous dermatosis (7%). The median age at diagnosis and male-to- female ratios, respectively, for AIBD subtypes were 68 years and 1:2.3 (bullous pemphigoid), 55.5 years and 1:1 (pemphigus foliaceous), 46 years and 1:3.3 (pemphigus vulgaris) and 16 years and 1:0.7 (linear IgA bullous dermatosis). Per annum, there was a mean of 18.8 new AIBD cases. Conclusion Few new AIBDs are diagnosed in Johannesburg, predominantly in older, Black African females. Subepidermal bullous disease, specifically bullous pemphigoid, is the most common AIBD, while pemphigus foliaceous is the predominant intraepidermal bullous disease.