Purpose: Malignant transformation to squamous cell carcinoma (SCC) arising within cutaneous epidermal cysts is a very rare phenomenon. We provide a series of new cases and an overview of the literature. We sought to define the prevalence of and characterize SCC arising within epidermal and pilar cysts.
Patient and methods: We searched Henry Ford Health System (HFHS) non-melanoma skin cancer (NMSC) registry from 2005 to 2009 to identify cases of SCC arising from epidermal cysts.
Results: We identified 1904 cases of epidermal cysts at our institution between 2005 and 2014. Of these, three cases of SCC arose from an epidermal cyst and one case of SCC developed from a pilar cyst. All lesions occurred below the waist with the exception of the pilar cyst on the scalp.
Conclusions: Given the extremely low incidence, propensity of malignant lesions to become symptomatic and efficacy of treatment, we do not recommend routine excision of all epidermal cysts. Instead, we recommend excision and pathology for all symptomatic epidermal cysts, or those that rapidly grow, or do not respond to medical therapy.
Keywords: Case series; epidermal cyst; literature review; pilar cyst; squamous cell carcinoma.