Squamous cell carcinoma arising from an epidermal cyst

MY Chiu, ST Ho
Department of Orthopaedics and Traumatology, Caritas Medical Centre, Shamshuipo, Hong Kong

There are few case reports in the English literature concerning malignant transformation of an epidermal cyst into squamous cell carcinoma. We report a case of squamous cell carcinoma arising from a 40-year epidermal cyst in the proximal left thigh of a 74-year-old man. The epidermal cyst had increased in size in the previous 3 years. The patient presented with a discharge from the lesion. Ultrasonography and magnetic resonance imaging of the lesion suggested malignancy. An intra-operative frozen section of an incisional biopsy of the lesion found it to be an epidermal cyst with suspected malignant change, so a marginal excision of the lesion was performed. Squamous cell carcinoma arising from the epidermal cyst was confirmed histologically. A wide excision was done in order to obtain an adequate resection margin. A computed tomographic scan of the thorax and abdomen found no evidence of metastases. No evidence of recurrence was noted in the latest follow-up, 2 years postoperatively.

Hong Kong Med J 2007;13:482-4

Key words: Carcinoma, squamous cell; Epidermal cyst; Skin neoplasms