Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 51, Num. 2, 2003, pp. 292

Neurology India, Vol. 51, No. 2, April-June, 2003, pp. 292

Letter to Editor

Congenital cholesteatoma

M. B. Popli, V. Popli
Department of Radiology, Health Centre, INMAS and Department of Pediatrics, LNJP Hospital, Delhi.

Accepted on 13.02.2002.

Code Number: ni03101

Sir

A 6-year-old boy had right ear otalgia for 3-4 weeks. No external pathological feature was present. The tympanic membrane was normal on otoscopy. Audiometric studies of the affected side revealed conductive deafness. CT showed a hypodense expansile lesion, extending from the middle ear cavity and eroding the petrous bone (Figure 1). The lesion extended to the right mastoid bone and into the posterior fossa.

The lesion had attenuation value higher than that of CSF with negative attenuation value at places. T1-weighted MR images showed a hypointense mass having thin curvilinear strands within it (Figure 2). On T-2 weighted images, the mass was hyperintense. Surgery confirmed the lesion to be a cholesteatoma.

Congenital cholesteatoma is rare. It arises from aberrant epithelial remnants left at the time of the closure of the neural groove between the third and fifth week of fetal life. Most often it has an intradural location, and less frequently (20%) an extradural location. Extradural congenital cholesteatomas are mostly found in the temporal bone, which is the most frequent site in the skull base. There are five general sites of occurrence within the temporal bone: the middle ear, the external auditory canal, the mastoid, the squamous portion of the temporal bone and the petrous apex.

On CT, congenital cholesteatomas are non-enhancing, hypodense, well-demarcated and expansile lesions. The density may have negative values reflecting fat content or values slightly higher than CSF, reflecting presence of proteinaceous material derived from desquamated epithelial cells. If the lesion is extramural in location sharply defined temporal bone erosion is seen. On MR images, the signal intensities match that of CSF.

Congenital cholesteatoma of the temporal bone should be distinguished from acquired cholesteatoma and cholesterol granuloma. In congenital and acquired cholesteatoma the histological findings are similar. Distinction is made according to the clinical criteria. Intact tympanic membrane, absence of previous otological disease, absence of tympanic membrane perforation or surgery, is necessary to consider a cholesteatoma to be congenital. Acquired cholesteatoma occurs in the middle ear cavity and rarely extends to the petrous apex.^1,2

REFERENCES

1. Martin C, Prades JM, Bertholon P, Merzougui N, Durand M. Intrapetrous cholesteatoma. Rev Laryngol Otol Rhinol Bord 1996;117:157-63.
2. Robert Y, Dubrulle F, Caracasset S, et al. Petrous bone extension of middle ear acquired cholesteatoma. Acta Radiol 1996;37:166-70.

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