Answer for BIR CoW 18 Sep 2022
Congenital cholesteatoma
Findings
Evidence of T1 isointense, T2 hyperintensity noted involving left middle ear, extending to epitympanum, aditus, antrum and left mastoid. It shows restricted diffusion with low ADC values. A thin collection is noted in left mastoid region outside the cortex, tracking through a 4 mm defect in the bony cortex. The collection in the mesotympanum is seen abutting the eustachian tube orifice anteriorly. No evidence of tegmen tympani erosion or intracranial extension IMPRESSION: Congenital cholesteatoma with cortical defect causing mastoid fistula.
Discussion
Cholesteatoma is a well-marginated non-neoplastic lesion which usually affects the middle ear, and much less commonly, develops in the external auditory canal. Cholesteatoma can be classified as either congenital or acquired based on pathogenesis. Middle ear congenital cholesteatoma is a relatively rare disease that accounts for approximately 2% of all middle ear cholesteatomas, and presents in children as a whitish mass behind an intact tympanic membrane. The current established criteria for diagnosis for a congenital cholesteatoma was described in 1986 by Levenson et al, who modified the original criteria of Derlacki and Clemis from 1965. The criteria now include a sac medial to an intact tympanic membrane in a patient who has never had a previous tympanic membrane perforation, otorrhea, or prior otologic surgery. Prior otitis media does not completely exclude the diagnosis. These lesions are most often unilateral, though bilateral lesions have been reported. Several mechanisms have been proposed to explain the pathogenesis of congenital cholesteatoma, including persistent epidermoid cell rest, ingrowth of meatal epidermis, and reflux of amniotic fluid. Of these, the favored theory of pathogenesis appears to be the persistence and continued growth of the epidermoid formation that normally exists in the middle ear during fetal life and usually disappears after 33 weeks of gestation. Congenital cholesteatomas have imaging characteristics similar to those of epidermoid cysts. MRI shows sharply demarcated margins with smooth bony erosions. On T1 it shows low signal. T2 weighted images show high signal (usually slightly brighter than CSF) and usually will not attenuate on FLAIR imaging, however partial or heterogeneous attenuation may occur. This is in contrast to cholesterol granulomas which never attenuate. Contrast administration shows no enhancement of the mass itself; thin linear enhancement confined to the margins may be seen. DW MRI is particularly sensitive to cholesteatoma tissue. Numerous reports abound in medical literature establishing the role of DW Imaging in diagnosis of intracranial and extracranial epidermoid cysts. As middle ear cholesteatomas have similar histopathological characteristics to epidermoid cysts this MR sequence forms the mainstay of imaging work up in these conditions. Conductive hearing loss is the most common presenting symptom. Treatment of congenital cholesteatomas is still surgical.
REFERENCES
1. K. Baráth, A.M. Huber, P. Stämpfli, Z. Varga, S. Kollias. Neuroradiology of cholesteatomas. AJNR Am J Neuroradiol, 32 (2011), pp. 221-229
2. Chapman P, Shah R, Curé J, Bag A. Petrous Apex Lesions: Pictorial Review. AJR Am J Roentgenol. 2011;196(3_supplement):WS26-37.
3. Tzek C, Meves T, Fitzek S, Mentzel HJ, Hunsche S, Stoeter P. Diffusion-weighted MRI of cholesteatomas of the petrous bone. J Magn Reson Imaging. 2002;15:636–641.
4. A. Tada, R. Inai, T. Tanaka, Y. Marukawa, S. Sato, K. Nishizaki, S. Kanazawa. The difference in congenital cholesteatoma CT findings based on the type of mass, Diagnostic and Interventional Imaging, Volume 97, Issue 1, 2016, Pages 65-69, ISSN 2211-5684
5. Kazahaya K, Potsic WP. Congenital cholesteatoma. Curr Opin Otolaryngol Head Neck Surg. 2004;12(5):398-403.
Findings
Evidence of T1 isointense, T2 hyperintensity noted involving left middle ear, extending to epitympanum, aditus, antrum and left mastoid. It shows restricted diffusion with low ADC values. A thin collection is noted in left mastoid region outside the cortex, tracking through a 4 mm defect in the bony cortex. The collection in the mesotympanum is seen abutting the eustachian tube orifice anteriorly. No evidence of tegmen tympani erosion or intracranial extension IMPRESSION: Congenital cholesteatoma with cortical defect causing mastoid fistula.
Discussion
Cholesteatoma is a well-marginated non-neoplastic lesion which usually affects the middle ear, and much less commonly, develops in the external auditory canal. Cholesteatoma can be classified as either congenital or acquired based on pathogenesis. Middle ear congenital cholesteatoma is a relatively rare disease that accounts for approximately 2% of all middle ear cholesteatomas, and presents in children as a whitish mass behind an intact tympanic membrane. The current established criteria for diagnosis for a congenital cholesteatoma was described in 1986 by Levenson et al, who modified the original criteria of Derlacki and Clemis from 1965. The criteria now include a sac medial to an intact tympanic membrane in a patient who has never had a previous tympanic membrane perforation, otorrhea, or prior otologic surgery. Prior otitis media does not completely exclude the diagnosis. These lesions are most often unilateral, though bilateral lesions have been reported. Several mechanisms have been proposed to explain the pathogenesis of congenital cholesteatoma, including persistent epidermoid cell rest, ingrowth of meatal epidermis, and reflux of amniotic fluid. Of these, the favored theory of pathogenesis appears to be the persistence and continued growth of the epidermoid formation that normally exists in the middle ear during fetal life and usually disappears after 33 weeks of gestation. Congenital cholesteatomas have imaging characteristics similar to those of epidermoid cysts. MRI shows sharply demarcated margins with smooth bony erosions. On T1 it shows low signal. T2 weighted images show high signal (usually slightly brighter than CSF) and usually will not attenuate on FLAIR imaging, however partial or heterogeneous attenuation may occur. This is in contrast to cholesterol granulomas which never attenuate. Contrast administration shows no enhancement of the mass itself; thin linear enhancement confined to the margins may be seen. DW MRI is particularly sensitive to cholesteatoma tissue. Numerous reports abound in medical literature establishing the role of DW Imaging in diagnosis of intracranial and extracranial epidermoid cysts. As middle ear cholesteatomas have similar histopathological characteristics to epidermoid cysts this MR sequence forms the mainstay of imaging work up in these conditions. Conductive hearing loss is the most common presenting symptom. Treatment of congenital cholesteatomas is still surgical.
REFERENCES
1. K. Baráth, A.M. Huber, P. Stämpfli, Z. Varga, S. Kollias. Neuroradiology of cholesteatomas. AJNR Am J Neuroradiol, 32 (2011), pp. 221-229
2. Chapman P, Shah R, Curé J, Bag A. Petrous Apex Lesions: Pictorial Review. AJR Am J Roentgenol. 2011;196(3_supplement):WS26-37.
3. Tzek C, Meves T, Fitzek S, Mentzel HJ, Hunsche S, Stoeter P. Diffusion-weighted MRI of cholesteatomas of the petrous bone. J Magn Reson Imaging. 2002;15:636–641.
4. A. Tada, R. Inai, T. Tanaka, Y. Marukawa, S. Sato, K. Nishizaki, S. Kanazawa. The difference in congenital cholesteatoma CT findings based on the type of mass, Diagnostic and Interventional Imaging, Volume 97, Issue 1, 2016, Pages 65-69, ISSN 2211-5684
5. Kazahaya K, Potsic WP. Congenital cholesteatoma. Curr Opin Otolaryngol Head Neck Surg. 2004;12(5):398-403.
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!