Wk 4, Case 4 - Review

Patient History
Left conductive hearing loss.

Findings
Noncontrast CT was performed of the temporal bones.

Right Temporal Bone: The external auditory canal is normally developed and normally formed. The mastoid air cell is well aerated. The middle ear cavity is well developed and well aerated. The ossicles are intact. The oval window is normally formed. The cochlear appears to have 2 1/2 turns with a normal appearing modiolus. The vestibule appears normal. The posterior, superior and lateral semicircular canals are intact. No evidence of superior semicircular canal dehiscence. No evidence of enlarged vestibular aqueduct. No definite evidence of fenestral or retrofenestral otosclerosis. No evidence of labyrinthitis ossificans. The internal auditory canal appears normal.

Left Temporal Bone: There is a focal soft tissue mass involving the left middle ear cavity which erodes the long process of the incus. The mass also extends to the region of the oval window and erodes suprastructure of the stapes including the anterior and posterior crus. The lesion extends anteriorly to involve a portion of the protympanum. The mass has minimal involvement of the sinus tympani. The mass extends superiorly into the anterior portion of the epitympanum and appears to slightly laterally displace the incudomalleolar joint and may demonstrate early erosion. There is also diffuse mucosal thickening involving the left mastoid air cells.

Overall, the left mastoid air cells appear to be underpneumatized compared to the right with signs of chronic osteitis. The mucosal thickening extends into the aditus ad antrum and extends to the tegmen mastoideum. MR would be helpful to determine whether or not there is extension into the inferior portion of the middle cranial fossa. Inferiorly, this mucosal thickening extends into the distal aspect of the mastoid air cells. There does appear to be some erosion of the septa of the mastoid air cells. Thus, this abnormality could also represent either diffuse chronic mucosal thickening or possibly large cholesteatoma. These findings can be further evaluated with MR of the temporal bone with diffusion if clinically indicated.

Conclusions
1. Focal soft tissue mass associated with ossicular erosion of the long process of the incus and stapes superstructure which is consistent with cholesteatoma and could result in a 30 decibel conductive hearing loss.
2. Diffuse mucosal thickening associated with likely erosion of the mastoid septa and underpneumatized left mastoid air cells. These findings could represent diffuse chronic mucosal thickening or large cholesteatoma involving the mastoid air cells.
3. MRI of the internal auditory canal could help further evaluate the superior extent of the mastoid disease to determine whether there is extension into the middle cranial fossa and could also help separate chronic mucosal thickening involving the mastoid air cells from cholesteatoma.