A man in his 40s presented with a 2-year history of gradual-onset, left-sided hearing loss. It was associated with a whistling tinnitus and occasional sharp otalgia lasting for a few minutes, approximately twice a week, without otorrhea. He reported labyrinthitis 2 years previously with possible reduced hearing afterward. He took no regular medications, had no allergies or clinically significant family history, and was an occasional smoker and alcohol drinker. Examination showed a smooth mass behind the left tympanic membrane. Findings from flexible nasoendoscopy were unremarkable. There was no palpable lymphadenopathy. Pure-tone audiometry demonstrated a mixed hearing loss on the left side. Results from tympanometry of the left ear were normal. A computed tomographic scan showed an expansile ground-glass density lesion arising within the lateral aspect of the otic capsule on the left (Figure, A and B). The lesion eroded into the lateral aspect of the basal and second turns of the cochlea as well as the tympanic portion of the facial nerve canal. Magnetic resonance imaging demonstrated a 7 × 8-mm lesion arising from the otic capsule, with mild uniform enhancement following gadolinium. A technetium bone scan showed a lesion in the temporal bone, and a focus of increased uptake in the left lateral eighth rib (no fracture was demonstrated) (Figure, C). To obtain a diagnosis, a bony sample was obtained, which consisted of small fragments of woven bony tissue with mild osteocyte nuclei enlargement and hyperchromasia, with no sign of neoplasia.
Yuen J, Burgess C, Bottrill I. An Uncommon Lesion of the Otic Capsule. JAMA Otolaryngol Head Neck Surg. 2016;142(4):395-396. doi:10.1001/jamaoto.2015.3296