Squamous cell carcinoma arising in a cutaneous epidermal cyst: case report and literature review.

Although cutaneous epidermal (infundibular) cysts are extremely common lesions, neoplastic transformation of their epithelium is quite rare. We describe a patient with a squamous cell carcinoma arising in the wall of an otherwise conventional epidermal cyst. In addition, we review the literature concluding that most of the previously reported cases may not correspond to this rare occurrence.