Prevalence of squamous cell carcinoma in patients with chronic hidradenitis suppurativa A review of the articles found 85 cases of SCC arising from HS reported in the English literature to date (6-13). A 2016 report by Jourabchi et al. (6) described 80 of these cases, and we found five additional cases published since that time (Table 2). Among these five new cases, the mean history of HS prior to SCC diagnosis was 26 years. The mean age at diagnosis was 52 years. SCC developed from longstanding HS of predominately the gluteal and perianal areas. A biopsy of malignant tissue was tested for human papillomavirus (HPV) in two of the five cases, and was negative in both cases. A history of tobacco use was reported in two cases (9, 10). The diagnosis of SCC in chronic HS is particularly challenging because painful and inflammatory HS lesions may be difficult to distinguish from malignant transformation (6). Thus, a low threshold for biopsy is often recommended by clinicians to diagnose