Primary angiocentric/angioinvasive T-cell lymphoma of the tympanic bulla in a FeLV positive cat

Introduction: Reports of primary middle ear lymphoma are rare in cats and their extension to internal organs is exceptional. A 5-yearold, neutered female, FeLV-positive domestic shorthair cat was referred for stertor, dyspnoea and head-tilt. CT scan revealed soft tissue opacity inside the right tympanic bulla with bone lysis and concurrent nasopharyngeal and intracranial invasion. Materials and Methods: Endoscopic-guided biopsy samples were collected for histology and immunohistochemistry. A full necropsy examination was performed. Results: Grossly, the lesion was poorly demarcated, white and soft. Cytology identified round, large, plasmacytoid neoplastic cells. Histology revealed dense sheets of round neoplastic cells often surrounding or invading vascular walls (angiocentric/angiodestructive pattern). Neoplastic cells expressed CD3 (T cell phenotype) and FeLV p27 and gp70 antigens. A middle ear angiocentric angioinvasive T-cell lymphoma was diagnosed. Following radiation therapy, clinical conditions improved, but dysphagia recurred and the cat died suddenly. At necropsy examination, a soft, red mass filled the ventromedial compartment of the tympanic bulla. Extension to the base of the skull with right piriform lobe compression was recorded. Hepatic and splenic metastases were present. Conclusions: Diagnosis of primary middle ear tumors is often delayed since clinical signs mimic more common otological conditions. Multiple biopsy specimens and immunohistochemistry were pivotal for the diagnosis in this case. FeLV might have been involved in tympanic lymphoma development.