title: Locations of primary cholesteatoma.
abstract: Primary cholesteatomas (PCs) are embryologic residual nests in the middle ear cleft. Based on a study of 56 cases (48 of them from the literature), a new classification is suggested: tympanic cavity PC (71% of the cases), and temporal bone PC (29%). Among the tympanic cavity cases a significant number (63%) were found in the anterosuperior quadrant. The findings support the embryologic theory for the origin of PC.
mesh_terms: D000328:Adult; D002648:Child; D002675:Child, Preschool; D002781:Cholesteatoma / Q000145:classification / Q000473:pathology*; D004427:Ear Diseases / Q000473:pathology*; D004432:Ear, Middle / Q000473:pathology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D013701:Temporal Bone / Q000473:pathology*