Epidermoid/Dermoid Cysts

Abstract

Intraspinal epidermoids were reported first in 1829. Epidermoids are rare tumors, amounting to 0.6% in the material of Cushing (1935), 0.66% in that of Foerster (1937), 1.8% in that of Tönnis’ (1937) and 1.5% in that of Zülch (1939). The dermoids are even rarer, accounting for only 0.15% in the material of Cushing, and in that of Zülch [4]. Percival Baily was probably the first to publish an account of a successful operation for epidermoid (cholesteatoma, inclusion cyst, or pearly tumor) of the brain. Numerous reports on operations for epidermoid are to be found in the pre-CT/MR era, when it was generally agreed that, although complete extirpation of the tumor including the capsule was the ideal treatment, this was not often feasible, except in cholesteatomas of the calvarium. In intradural tumors it was rarely possible to remove the capsule completely because of its adherence to the blood vessels and sensitive nervous tissue [4]. With the advent of modern imaging and micro-neurosurgery, the proportions of epidermoids and dermoids identified within intracranial tumors have increased. However, they still acount for fewer than 2% of intracranial tumors. The ratio of intracranial epidermoids to dermoids is 4∶1, with epidermoid tumors typically becoming symptomatic during the third and fifth decades, whereas dermoids tend to occur in the paediatric age group. While the pioneers of macro-neurosurgery warned that complete extirpation of the capsule is practically never advisable or possible when the tumor was situated in brain areas adjacent to important blood vessels or cranial nerves, the goal of micro-neurosurgeons has been complete resection with as little morbidity as possible [10].