- Terminology
- Synonym : otospongiosis
- Types : Fenestral ostosclerosis (FOto), cochlear otosclerosis (COto)
- Pathologic appearance of lytic spongy bone foci in bony labyrinth of unknown cause
- Starts perifenestral (FOto), progresses to surround cochlea (FOto + COto)
- Fissula ante fenestram : cleft to fibrocartilaginous tissue between inner & middle ears just anterior to oval window
- Imaging findings
- Osteolytic lesion on temporal bone CT scan
- Fenestral otosclerosis : starts at anterior margin of oval window (fissula ante fenestram)
- Cochlear otosclerosis : Affects pericochlear bony labyrinth
Right) Fenestral otosclerosis with a “donut” otospongiotic plaque surrounding the stapes footplate in the oval window.
Reference)
Koch et al. Diagnostic Imaging: Head and Neck 3rd edition, Elsevier, 1120-1121.
