by: Dr. Alice Runk, DVM, Dipl. ACVS
Masses in the ear canals of cats are common and cause scratching at the ear, shaking the head and sometimes ear discharge. On otic exam, they appear as a pink or red, fleshy mass in the ear canal. It is often difficult during otic exam to determine the source of the mass – either the lining of the ear canal or the bulla.
The most common types of ear masses are inflammatory polyps which arise from the bulla and ceruminous gland adenocarcinoma/adenoma and squamous cell carcinoma which arise from the lining of the ear canal.
A critical step in determining the proper surgery for treatment is obtaining a biopsy to determine the definitive diagnosis. A biopsy is easy to obtain with the cat under general anesthesia. The mass is viewed with the otoscope and a small cupped biopsy forcep is placed down the otoscope to “grab” small pieces of the mass for histopathology. There is often mild, self-limiting bleeding from the mass after biopsy. The histopathology results are then used to determine the proper surgery to treat the patient.
Inflammatory polyps arise from the bulla and can extend through the eardrum into the ear canal or down the eustachian tube into the throat. The definitive surgical treatment is a ventral bulla osteotomy to remove the base of the polyp and the lining of the bulla to prevent recurrence.
Ear canal neoplasia such as ceruminous gland tumors and squamous cell carcinoma are best treated with a total ear canal ablation and lateral bulla osteotomy. A pre-operative CT scan is not mandatory but can be useful in determining whether the tumor has eroded through the ear cartilage and invaded surrounding bone or soft tissue. The ear canal cartilage acts as a very good natural barrier and often contains the tumor to the interior of the canal. If the tumor has not eroded through the cartilage – the long-term prognosis is very good with total ear canal ablation surgery. If the tumor has extended into the surrounding tissues, then surgery may not be beneficial or may offer short term palliation only.
Since these two surgical procedures are vastly different in surgical approach, invasiveness, cost and potential complications, the pre-operative biopsy is critical in presenting the proper treatment to the pet owner.