Classification:
Congenital (2%)
Acquired (98%)
--Pars flaccida (82%)
--Pars tensa (18%)
---- Posterosuperior (78%)
---- Anteroinferior (22%)
Congenital cholesteatoma:
= Epidermoid Epithelial rest cells
Can be seen in middle ear, mastoid, squamous temporal, petrous apex, CP angle
Common in anterior middle ear cavity near ET tube and stepes
Acquired cholesteatoma:
= Prusaac's cholesteaoma, attic cholesteatoma
Sequele to middle ear infection
MRI:
Useful in evaluating post operative/ recurrent cholesteatomas; differentiating
Delayed post-Gd T1 SE is useful
Cholesterol granuloma: increased signal on T1, no change on delayed Gd T1, low signal on DWI
with b factor of 800 sec/mm2.
Granulation tissue without recurrence: low signal on T1, high signal on T2, enhance on delayed
Gd T1, low signal on DWI b factor of 800 sec/mm2
Recurrent cholesteatoma: low signal on T1, no change on delayed Gd T1, and high signal on DWI
with b factor of 800 sec/mm2
Cholesteatoma shows increased signal on DWI, whereas granulation tissue, fibrous tissue, cholesterol granuloma, or serous fluid show low
signal intensity.
Reference:
http://radiology.rsnajnls.org/cgi/content/full/238/2/604
Diffusion-weighted MR Imaging Sequence in the Detection of Postoperative Recurrent Cholesteatoma
Radiology 2005;238:604-610
