SIGNIFICANCE OF EPIDERMOID FORMATIONS IN THE MIDDLE-EAR IN FETUSES AND CHILDREN

Objective: To determine the incidence, size, and location of epidermoi d formations (EFs), which have been suggested to be precursors of cong enital cholesteatomas, in temporal bones from fetuses and children. De sign: We examined temporal bones from 226 fetuses and children up to t he age of 10 years for the incidence, size, and location of EFs. Resul ts: Twenty-five EFs were identified in middle ears of 3 fetuses, 7 neo nates, 9 infants, and 2 children aged 2 and 3 years. There was a male- female preponderance of 5:4. Generally, we saw EFs between the anteros uperior edge of the eardrum and the anterior Limb of the tympanic ring , but 4 were below the level of the handle of the malleus. Their width s ranged from 25 to 300 mu m. Keratinization was not observed in any E F. Contrary to previous reports, we found EFs not only in ears of fetu ses, but also in ears of infants and children. Conclusion: Although EF s may persist in some ears, possibly developing into congenital choles teatomas, our findings do not provide direct support for this concept.