Squamous Cell Carcinoma Arising in an Epidermal Cyst

To the Editor.— Squamous cell carcinoma arising in an epidermal cyst, although not rare, is unusual in occurrence. I had the opportunity of treating a patient with a well-differentiated carcinoma in a long-standing sebaceous cyst. There was a 25-year period of follow-up evaluation during which the patient had had no recurrence of the lesion. Report of a Case.— A 34-year-old man, admitted to the hospital on Feb 21, 1955, had had a mass on the left posterior side of his head for 20 years. Considerable enlargement of the tumor had occurred during the two years before admission. Physical examination disclosed a lesion 8 cm in diameter and 3 cm high (above the level of the scalp). Fluctuation and a fluid wave were easily demonstrable. Palpation suggested that the outer table of the skull under the mass was eroded. Roentgenograms defined scattered areas of calcification in the mass. A moderate degree