Migration of intradural epidermoid matrix: embryologic implications.

The migratory behavior of acquired cholesteatoma matrices (those arising from the tympanic membrane) has been described previously. This tissue is derived embryologically from the first branchial groove and represents the only migratory epithelium arising from the branchial groove system. If the matrix from a cerebellopontine angle (CPA) epidermoid tumor exhibits migratory behavior similar to that of acquired cholesteatomas, a first branchial groove site of origin for CPA epidermoids would be supported. Intradural CPA epidermoid cells were grown in alpha-minimum essential medium. The cultures were examined daily, and cell mass migration rates were measured. It was observed that intradural epidermoid tumor matrix harvested from the CPA exhibited migration in vitro. Its migratory properties were indistinguishable from those of acquired cholesteatomas, which are embryologically derived from the first branchial groove. These data support the theory that purely intradural epidermoids are derived from cells of the first branchial groove.