Cholesteatoma is an accumulation of stratified squamous epithelium in the middle ear, comprising both living cellular matrix and the dead keratinous layer. There are two types of cholesteatoma acquired and congenital. The pathogenesis of cholesteatoma is still not well understood. One theory of development of congenital cholesteatoma is Michaels’ theory of epidermoid formation. The epidermoid foci are at the same site asmany congenital cholesteatomas, i.e. in the anterior superior part of the middle ear. In our study 92 foetal temporal bones were examined and epidermoid formation was found in 16 i.e. 17%. We found 39 epidermoid formations in 16 temporal bones, thus there were several epidermoid foci, in one temporal bone (maximum 7). The epidermoid formations presented several configurations: 21 superficial, 13 spherical and mixed, 4 elongated into the subepitheliumand one intraepithelial. Twenty - one epidermoid formations (53.8%) were at the most typical site e.g. in the anterior superior part of the middle ear. The gestational age of the foetuses were from 13 to 42 weeks.We did not find any epidermoid formation after the 33rd week of gestation.

        Key words: epidermoid formation, temporal bone, foetus, middle ear, histology, cholesteatoma.