A histopathological analysis of granulomatous dermatoses – a single centre experience from Sri Lanka

Granulomatous inflammation is a common histological pattern encountered in skin biopsies which pose a diagnostic challenge to pathologists because of overlapping histological features produced by various aetiological agents. We conducted the following study to analyze the aetiological factors and morphological patterns of granulomatous dermatoses in a cohort of Sri Lankan patients from the Central Province. This is a retrospective analysis of skin biopsies dectected to have granulomatous inflammation over a 12 year period at the Department of Pathology, Faculty of Medicine, University of Peradeniya. All biopsies had been assessed using haematoxylin and eosin stain and special stains when necessary. Of the 1547 skin biopsies received, 128 (8.3%) were recognized to have granulomatous inflammation. An infectious aetiology was present in 86.7% (111/128).The most prevalent infectious cause was leprosy, accounting for 39.8% (51/128) followed by the category differential diagnoses in 22 (17.1%) of which had an infectious differential. Cutaneous tuberculosis was the cause in 17 (13.3%) cases. In 102 cases (79.7%) necrosis was absent in the granulomata and when present most were (58%) of suppurative type; typical caseous type necrosis was present in only a few cases. In conclusion, a large majority of granulomatous inflammation is due to infectious causes and leprosy is the leading cause in this study cohort.