Cutaneous squamous cell carcinoma complicating hidradenitis suppurativa: a review of the prevalence, pathogenesis, and treatment of this dreaded complication.

Hidradenitis suppurativa (HS) is a chronic and debilitating skin disorder characterized by the formation of painful abscesses, draining sinus tracts, and scarring, predominantly in skin folds such as the axillae and the perineum. The exact prevalence of HS is unknown because the disease is often underreported, but it has been estimated to be as high as 4.1%. HS is three times more prevalent in women than in men. Various comorbidities have been associated with HS, including inflammatory bowel disease and squamous cell carcinoma (SCC). The transformation of chronic HS to SCC is often considered the most severe complication of HS. The prevalence of SCC associated with HS is approximately 4.6%, and is more common among men. It is likely that the chronic irritation and inflammation characteristic of HS drive the malignant transformation to SCC, and recent work has identified other potential risk factors for this malignant transformation, including human papillomavirus (HPV) infection and tobacco use. Treatment modalities have expanded in recent years to include triple antibiotic therapy, immunomodulatory biologic agents, laser therapy, and surgical excision. Knowledge of these comorbid associations of HS, especially the malignant transformation to SCC, is highly important for the management and follow-up of this chronic disease.