Atypical, abscessated nasopharyngeal polyp associated with expansion and lysis of the tympanic bulla.

A 5-year-old, male neutered domestic shorthair cat was referred for investigation of lethargy, weight loss, pyrexia and upper respiratory tract signs. On computed tomography, an expansile, osteodestructive lesion in the right tympanic bulla was identified. A soft tissue mass extended from the bulla into the nasopharynx, cranium and subcutaneous tissues. The nasopharyngeal mass ruptured during handling, liberating purulent material from which Pasteurella multocida was isolated in pure culture. The lesion was most likely an atypical, abscessated nasopharyngeal polyp. The cat was treated with bulla osteotomy and antibiotics, and made a complete recovery.