Ceruminous Gland Tumors
(Ceruminous gland adenoma or adenocarcinoma)
Ceruminous gland tumors are best visualized in a degreased, clean ear using a video otoscope. These tumors may be pedunculated or broad based but rise above the level of the epithelium. They may be smooth or multilobulated in appearance. In breeds other than the American Cocker Spaniel, these tumors are often primarily in the vertical ear canal. In the American Cocker, these tumors can be found in the horizontal ear canal as well. Properly taken, ear canal biopsies can give useful information. However, superficial ear canal biopsies are often reported as polyps with granulation tissue covered by epithelium. Deep en-bloc biopsies of the same tissue are often reported correctly as tumors. CT or MRI may be very useful in assessing the tympanic bulla more completely and in determining the extent of tumor invasion, especially in malignant tumors.
Surgical removal of benign ear canal tumors may be accomplished via lateral ear canal resection for access to the tumor mass. Laser surgery, especially when used in conjunction with a video otoscope, has made intraotic removal of these tumors relatively easy without having to open the canal surgically. More aggressive surgeries, such as total ear canal ablation and bulla osteotomy, are recommended for malignant tumors of the middle ear. Lateral ear canal resection for malignancies results in a >75% recurrence rate. Median survival time for animals with malignant ear canal tumors has been reported to be >58 mo in dogs and >11.7 mo in cats. Dogs with extensive tumor involvement had a less favorable prognosis. Radiation therapy can be used to treat excised ceruminous gland adenocarcinomas in dogs and cats, with a 56% 1-yr survival rate reported. No data are available on the efficacy of chemotherapy for otic tumors of dogs and cats.
Prognosis of animals with otic neoplasms can best be determined by histopathologic examination of removed tissues.