Clinico-histopathological review of cutaneous sarcoidosis: A retrospective descriptive study.

Background Sarcoidosis is a systemic, non-caseating granulomatous disease characterised by clinical and histopathological variability. Objective To review cases of cutaneous sarcoidosis and describe their clinical and histopathological features. Methods A retrospective study was conducted to analyse the clinical and histopathological frecords of all available skin biopsy slides signed out as 'sarcoidal tissue reaction' or 'sarcoidosis' from 2014 till 2022. Results A total of 25 cases were studied. The lesions were most commonly located on the head and neck (18 cases, 72%). Morphologically plaques (20%) were the most common, and the majority of cases had lesions of ≥2 distinct morphologies (44%). Histologically, classical naked granulomas were observed in 72% of cases. The granulomatous infiltrate was pandermal in 56% of cases, perivascular and interstitial in 16%, and perivascular, perieccrine, and interstitial in 12%. Granulomas with a 'leprosy' pattern were observed in 20% of cases. High-density granulomas (occupying >30% of the dermis) were present in 64% of cases. Fibrinoid necrosis and fibrosis between granulomas were observed in 16% and 8% cases, respectively. Inclusion bodies, such as asteroid and Schaumann bodies, were seen in 24% and 4% cases, respectively. Reticulin-rich granulomas were observed in 54% cases, while reticulin-poor granulomas were seen in 8.3%. Elevated serum ACE levels were found in 14 cases, and tuberculin skin test, conducted in 22 cases, was negative. Extracutaneous involvement was found in 11 cases, with 10 having pulmonary and 1 with pulmonary and splenic involvement. Limitation Retrospective nature of the study and small sample size. Conclusion Cutaneous sarcoidosis presents with a wide range of clinical and histomorphological features, necessitating clinico-histopathological correlation and ancillary investigations to establish the diagnosis and rule out mimickers.