The development of carcinoma in sebaceous cysts has been reported rather infrequently in the literature, and most of the studies are either small in number or reports of single cases. Several larger series2,4,5,12,15 have been reported either as a collection of consecutive cases or as a compilation from the literature. Our series of cases, while neither large nor small, contains several singular features which would seem to merit publication.
Incidence of Malignancy
The incidence of malignant change in sebaceous cysts cited in the various reports in the literature ranges from a high of 9.2%, recorded by Bishop,2 to a low of 0.033%, given by Collins,5 although the figure of 3.4%, cited by Caylor,4 seems to be the most reasonable and widely accepted.The frequency of malignant change in sebaceous cysts is difficult to determine, for at least two reasons. There is as yet no universally accepted