Multicentric B-cell lymphoma with otic involvement in 2 guinea pigs

Abstract

Objective

To describe the diagnosis, treatment, and outcome of 2 guinea pigs with an atypical presentation of multicentric B-cell lymphoma with otic involvement.

Animals

Archived postmortem and medical records were searched for guinea pigs diagnosed with lymphoma affecting the middle and inner ears between 2016 and 2022. Two guinea pigs initially presented with otitis media/interna signs, one 4-year-old male and one 3.5-year-old female.

Clinical Presentation

Both guinea pigs presented for acute inappetence with either a head tilt or upper respiratory signs. Skull CT findings in both guinea pigs were suggestive of bilateral otitis media. Bloodwork and cytology for both guinea pigs were consistent with hemic neoplasia. Ultimately, humane euthanasia was elected for both animals.

Results

Microscopically, in both guinea pigs, there were neoplastic lymphocytic infiltrates in both inner and middle ears, invading adjacent bone and skeletal muscle. The neoplastic cells were positive for CD79a on immunohistochemistry. Both animals also had moderate, diffuse, chronic heterophilic otitis media with tympanic bone remodeling.

Clinical relevance

While clinical and computed tomographic findings suggested bacterial otitis media and interna, both animals had marked otic infiltration with neoplastic lymphocytes as part of multisystemic disease. Multicentric lymphoma with otic involvement should be considered a differential in guinea pigs with evidence of middle and inner ear disease.