Intradiploic Epidermoid Tumors of the Cranium: Case Report with Review of the Literature

Abstract

Introduction Epidermoid cysts are a rare intracranial tumor, mostly arising from the cerebellar pontine angle but sporadically arising from the cranial diploe. Intradiploic epidermoids were first described in 1838 and have since been reported in sporadic case reports and case series. Due to the scarcity of cases, no institution has a large enough case series to fully characterize this tumor. We review numerous case series to better describe intradiploic epidermoids. Methods Using a search for intradiploic epidermoid, several case reports and series were found. References from these articles were reviewed for further cases. Results A total of 169 cases of intradiploic epidermoids were reviewed. The average age of patients presenting with intradiploic epidermoids was 38.1 years (standard error of the mean: 1.56). Overall, 68.9% of these patients presented with localized swelling over the scalp, 32.3% with headaches, and 42.7% with other neurologic symptoms. The most common location of the tumor was the frontal bones, with the least common the sphenoid, zygomatic, and maxillary bone. Surgical resection was curative in most cases, with a 3.2% mortality. Recurrence rate was only 5.8%, with nearly all occurring before 1999. Of the recurrent cases, malignant transformation to squamous cell carcinoma was estimated at 44% (4/9). Most of these cases are thought to have occurred as a result of incomplete resection of a primary intradiploic epidermoid. Conclusions To date, this is the largest review of intradiploic epidermoids reported in the literature. In the reported cases, most had a benign course. However, there are occasional malignant transformations, and some patients have neurologic sequelae from mass effect or tumor infiltration. This is a surgically curative tumor in most cases.