The most common neoplasm of the ear canal is ceruminal gland in origin. These neoplasms are more common in the cat than in the dog. One report noted that tumors of the ceruminous glands accounted for 40.7% of the histopathology of external ear masses evaluated in cats and are most often benign. The category ‘ceruminous cyst/hyperplasia’ accounted for 1.7% of all feline skin tumors in another large survey.
Malignant ceruminous gland tumors tend to be ulcerative and infiltrating rather than obstructive/occlusive. Ceruminous glands are located in the deeper dermis of the external ear canal. They are believed to be modified apocrine sweat glands that secrete waxy cerumen instead of watery sweat. In the normal dog and cat the ducts of the ceruminous glands are virtually non-visable.
The classic appearance of ceruminous hyperplasia is multiple, often numerous, punctuate nodules or vesicles, usually less than 2mm in diameter, in the external ear canal and inner pinna. They are dark blue, brown or black. They are usually confined to the external ear canal and rarely extend beyond the vertical canal.
Diagnosis is based on histological examination of biopsied tissue samples. These tumors are a simple benign apocrine tumor of the ceruminous glands in the ear of cats showing differentiation to ceruminous secretory epithelium.
Treatment involves either surgical debridement of the hyperplastic skin or carbon dioxide laser treatment followed by weekly ear cleaning, a hydrolised diet and intermittent topical corticosteroid drop to minimise the recurrence of the cysts. Squalane 25% in an isopropyl Myristate-liquid-petroleum base ear cleanser that could supply the ear topically with an oil, hopefully this would decrease production by the ceruminous glands thus minimizing the start of the hyperplasia process from constant production of material.
Surgery is usually reserved for more severe cases in order to remove the multiple occlusive nodules. Surgical options include lateral ear canal resection or total ablation of the ear canal or surgical removal of the affected pinnae. Tumors of the pinnae are often difficult to remove with conventional scalpel surgical excision without causing some disfiguration of the pinnae and sutures are usually required to control bleeding.
Carbon dioxide (CO2) laser vaporization is an effective therapy that is the least traumatic but most effective therapy. The CO2 laser has little to no collateral tissue damage when the laser is used properly making it an excellent choice for laser surgery. Laser ablation is the best mode of therapy because of the ability to fine tune the laser ablation by variation of the spot size, the power setting, and the duration of exposure. The laser surgeon is also able to limit removal to just the lesion, thereby avoiding damage to adjacent normal structures. Laser ablation results in much less scar formation, and thus little to no deformity of the pinnae. The CO2 laser is also well known for its excellent hemostasis and can effectively seal blood vessels less than 0.5mm. With the CO2 laser, hemostasis allows tumor removal without the need for sutures. The use of the CO2 laser minimizes any deformities to the pinnae allowing the ears to look normal. The CO2 laser in this author’s experience is definitely the treatment of choice for ceruminous gland hyperplasia masses of the ear pinnae. Food allergies can also play a role in ceruminous otitis and thus ceruminous gland hyperplasia and a food trial with a hydrolyzed protein or novel protein diet should be utilized for a minimum of 8 weeks.
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