A SMALL NUMBER of cases of cyst involving the mastoid process have been reported in the literature.1 Microscopic studies in these cases showed a cyst of either a dermoid or a sebaceous character. In some of the cases of dermoid cyst mentioned in the literature bony destruction of the mastoid bone was present, while in others the cyst was located in the subcutaneous layer only. The case of cyst of the mastoid process described in this paper is presented because no report of a similar case was found in the literature and because the clinical course and the examination in no way indicated the extensive pathologic process involving the dura and the petrous bone.
REPORT OF A CASE
A 17 year old white youth noticed a painless swelling behind his left auricle three months before his admission to the Presbyterian Hospital, New York. He had never experienced any pain or