Key findings in acquired and congenital middle ear cholesteatoma. From Radiopaedia.org and Diagnostic Imaging: Head and Neck by H. Ric, Harnsberger. https://radiopaedia.org/articles/cholesteatoma?lang=us https://radiopaedia.org/articles/congenital-cholesteatoma?lang=us https://radiopaedia.org/articles/acquired-cholesteatoma?lang=us https://radiopaedia.org/articles/prussak-space?lang=us

1. Middle ear cholesteatoma
Imaging findings
Maria Cucos MD

2. Types of middle ear cholesteatoma (ME Ch)
acquired
pars flaccida (PF)
pars tensa (PT)
congenital

3. Acquired cholesteatoma
secondary to chronic ME infection
and tympanic perforation
95% of all Ch and most frequent
ME-mastoid mass
80% in Prussak space
tympanic membrane not intact
 retracted or perforated
Congenital cholesteatoma
epidermoid inclusion cysts
5% of all Ch
petrous apex > ME
tympanic membrane intact

4. Cholesteatoma on CT
soft tissue mass
mass effect
bone erosions

5. Bone erosions to report in cholesteatoma
scutum
lateral wall of tympanic cavity
ossicles
mastoid
tegmen tympani
lateral semicircular canal
facial nerve canal
oval and round window

6. Acquired cholesteatoma
when ME and mastoid completely opacified
 difficult ddx effusion vs cholesteatoma
 ossicular erosion supports Ch
 but ossicular erosion can also happen with
chronic otomastoiditis
 scutum erosion further supports Ch

7. Pars flaccida cholesteatoma
more common than PT Ch
originates in Prussak space
 scutum erosion
extends posterosuperiorly
 epitympanum and mastoid
lateral to ossicles
 ossicle erosion starts laterally

8. Pars tensa cholesteatoma
if small, seen in facial recess and sinus tympani of
posterior wall of mesotympanum
often medial to ossicles
 ossicle erosion starts medially
spreads to ossicles, aditus, and mastoid

9. Consider PT Ch if
mass centered posteriorly, medial to ossicles
ossicles displaced laterally
ossicle erosion starts medially

10. Cholesteatoma on MRI
 think of epidermoid cysts in the brain
T1 hypo
T2 hyper
FLAIR no attenuation or only partial attenuation
≠ cholesterol granuloma which never attenuates
T1 C+ thin rim enhancement
DWI restricted diffusion with low ADC

11. Cholesteatoma on MRI
variant of congenital Ch: white epidermoid
T1 hyper, T2 hyper
indistinguishable from cholesterol granuloma

12. Complications of cholesteatoma
perilymphatic fistula
labyrinthitis
meningitis
cerebral abscess
petrous apicitis

13. Ask clinician about otoscopy
tympanic membrane intact or perforated/retracted?
color and location of retrotympanic mass

14. Remember
perforated/retracted tympanic membrane
soft tissue mass with bone erosions
Prussak space
diffusion restriction