Granulomatous Skin Diseases in a Tertiary Care Portuguese Hospital: A 10-Year Retrospective Study.

Granulomatous skin diseases comprise an extensive group of pathologies whose diagnosis usually requires a histopathological examination. At this level, various types of granulomas can be distinguished, namely tuberculoid, sarcoid, necrobiotic, suppurative, xanthogranuloma, and foreign-body granulomas. This study aimed to determine the frequency and pattern of different granulomatous skin lesions in the Dermatopathology Department of Hospital de Santa Maria (Lisboa, Portugal). A retrospective study of all skin biopsies with granulomatous lesions received during a period of 10 years (2008-2017) was performed. Clinical and histopathological characteristics of the selected cases were analyzed, and the lesions were categorized according to histological type of granuloma and etiology. Foreign-body granulomas secondary to ruptured cyst, folliculitis, or suture material were excluded. From a total of 48,253 cutaneous biopsies performed in this period, 461 (1%) granulomatous lesions were included in our study. In the analysis according to type of granuloma, necrobiotic granulomas were the most frequent (N = 111; 27.0%), followed by sarcoidal (N = 72; 17.5%), tuberculoid (N = 51; 12.4%), suppurative (N = 45; 10.9%), foreign body (N = 40; 9.7%), and xanthogranulomas (N = 26; 6.3%). The remaining 20% corresponded to granulomas of other types. During these 10 years, the most frequent etiology was granuloma annulare (N = 98; 88.3%), followed by sarcoidosis (N = 47; 65.3%). Histopathology is a fundamental tool in the diagnosis of granulomatous skin diseases, allowing for the categorization of various types of granulomas and often guiding further investigation of these patients. The geographical area has an influence on the types of granulomas observed, as evidenced by comparing this study with others previously published.