Abstract

Squamous cell carcinoma usually arises in sun exposed areas of the skin, however, uncommonly it may also develop in areas of chronic inflammation. Marjolin’s ulcer is a type of rare, aggressive squamous cell carcinoma presenting in an area of previously traumatized, chronically inflamed, or scarred skin. Moreover, malignant transformation has been identified in about 0.1% of patients with chronic pilonidal disease, with only less than one hundred reported in the literature. We present a case of a 65-year-old male with long standing history of a presumed pilonidal cyst, with recent changes of more discharge and pain. Clinical examination demonstrated a pilonidal lesion and a right groin mass. Initial punch biopsy showed invasive squamous cell carcinoma, with no evidence of epidermal origin. Leading to the differential diagnosis of metastatic squamous cell carcinoma, squamous cell carcinoma arising from a proliferating pilar tumor. On subsequent excision, it demonstrates an invasive squamous cell carcinoma arising from the epithelium of a pilonidal cyst. In addition, the right groin mass was biopsied to reveal a lymph node positive for metastasis. Although squamous cell carcinoma arising from a pilonidal cyst is exceedingly rare, one should be aware of its existence, and must be identified as it is extremely aggressive. In the instance of chronic cutaneous inflammation, with a clinical change of malignant transformation, malignancy must be ruled out.

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