Pathognomonic signs of cholesteatoma:
1-Non dependent mass:
If the mass is dependent, so it is fluid (otitis media).
2-Non enhanced mass:
If it is enhanced, it will be glomus tympanicum and not a cholesteatoma.
3-In diffusion weighted image, cholesteatoma will appears as a hyper intense lesion while in case of otitis media, it will appear as a hypo intense lesion, this is very important in case of severely affected middle ear, in such a case the surgeon needs an accurate diagnosis.
4-Congenital cholesteatoma can occur any where in the middle ear
( commonly near Eustachian tube and stapes ).
5-Acquired type occurs in two places:
*Prussak's space (95%).
*Sinus tympani (5%).
6-Look for erosion in tegmen tympani which could cause dural vein thrombosis or brain abscess.
7-Look for erosion in the lateral semi circular canal which may cause Labyrinthine fistula which means abnormal connection between middle and inner ear.
8-This fistula leads to infection of the inner ear causing labyrinthitis which is diagnosed only by MRI with contrast showing Labyrinthine enhancement.
9-Erosion of facial nerve at facial recess.
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| Non dependent, non enhanced mass seen in the middle ear cavity eroding lateral tympanic wall |
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| Black arrow pointed to oval window while white arrow is pointing to labyrinthine fistula connecting middle ear cavity to the inner ear. |
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