To the Editor: We read with great interest the article "Congenital Cholesteatoma in a Case of Congenital Aural Atresia" (Otol Neurotol 2006;27:934-936) by RJ Caughey, RA Jahrsdoerfer, and BW Kesser (1). Authors presented a case of an 8-year-old child with congenital cholesteatoma and congenital aural atresia. Our compliments on having diagnosed such an unusual case and achieving very good results of surgical treatment. We have several comments regarding their diagnosis and treatment paradigm. Incidence of congenital cholesteatoma is very low (2). Establishing the origin of cholesteatoma remains difficult and controversial. More often one can observe cholesteatomas in ears, where congenital abnormalities of the external auditory canal (EAC) are present. In a normal case, the ectoderm canalizes from medial to lateral to form the EAC. If this process is arrested, stenosis or atresia of the EAC is a result. In such developmental disorders, when tympanic membrane is not formed, ectodermal epithelium is "lost" next to tympanic cavity. This "lost" ectodermal epithelium may initiate the growth of cholesteatoma that later grows into tympanic cavity between ossicles. It is difficult to explain how squamous epithelium got into tympanic cavity; it is possible that this took place by the end of intrauterine life (2). We agree with author's suggestion that cholesteatoma grew as a result of the ear developmental disorders before 33rd week of intrauterine life (according to epidermoid formation theory of Michaels) (3). The origin and nature of cholestatoma may be assessed by MRI and by histopathological and molecular examinations. Magnetic resonance imaging finds the hyperintensity on T2-weighted images with little peripheral enhancement on post-contrast T1-weighted images. Huang et al. (3) in immunohistochemical examinations observed that epidermoid formation in human fetal middle ear had the same staining patterns of middle ear mucosa for CK13, CK18, and CK19, and they were different from the EAC skin. Authors suggest that hyperplastic epidermoid formation may acquire certain properties of epidermis and develop into congenital cholesteatoma. Liang et al. (4) showed that expression of the cytokeratine pattern of the epidermoid formation was found in a total of 116 of these structures in 22 temporal bones aged from 16 weeks to 8 months. Histopathological examination of congenital cholesteatoma may be valuable in distinguishing congenital and acquired cholesteatomas. Acquired and congenital cholesteatomas presented so far do not show convincing evidences for morphological differences between these two types of cholesteatoma. Congenital cholesteatoma mainly contains keratin masses and poorly developed matrix, without stroma. Matrix of congenital cholesteatoma contains from 2 to 5 layers of squamous epithelium, whereas acquired cholesteatoma contains many more of these layers. In the microphotography of cholesteatoma presented by authors, the matrix contains over a dozen layers of squamous epithelium. The assessment of telomeres length in keratinocytes would be helpful in distinguishing congenital and acquired cholesteatoma. Chromosomal telomers of congenital cholesteatoma are longer than telomers of acquired ones (5). Jerzy Kuczkowski, M.D., Ph.D. Waldemar Naroz˙ny, M.D., Ph.D. Boguslaw Mikaszewski, M.D., Ph.D. Department of Otolaryngology Medical University of Gdańsk Gdańsk, Poland