+ Signalment
- Mean age 9 years for benign tumors and 10 years for malignant tumors
- No sex predisposition ± male
- Breed predisposition: Cocker Spaniel (possible association with propensity for otitis externa) and Boxers
- Inflammation is a precursor to tumor development with increased glandular dysplasia
- Benign aural tumors: inflammatory polyp, papilloma, basal cell tumor, and ceruminous gland adenoma
- Malignant aural tumors: ceruminous gland ADC, SCC, and other cutaneous tumors
- Malignant tumors tend to be locally invasive with a low metastatic potential (10% to regional lymph node and lungs)
+ Clinical Signs
- Mass
- Aural discharge, odour, pruritis, and local pain
- Neurologic signs in 10% of dogs with malignant aural tumors
- Duration of clinical signs prior to presentation is usually prolonged (months to years)
- Benign tumors are usually raised and pedunculated with rare ulceration
- Malignant tumors usually have a broad base with ulceration and hemorrhage
- 25% of malignant tumors have bulla involvement
+ Diagnosis
- Otoscope
- Survey radiographs
- CT
+ Treatment
- Surgical resection
- TECA-LBO for malignant tumors
- Lateral or vertical ear wall resection for benign tumors
- Caudal auricular approach described for cholesteotoma
- Radiation therapy as either primary or adjunctive treatment
+ Prognosis
- Malignant aural tumors are less aggressive in dogs than cats
- Poor prognostic factors include bulla invasion, extensive tumor involvement, and conservative surgery
- Survival time significantly better for ceruminous gland ADC compared to SCC
- MST significantly better for tumors without extensive involvement (> 58 months v 5.3 months)
- MST (36 months v 9 months) and local tumor recurrence rate (0% v 75%) are significantly better for tumors treated with TECA-LBO compared to lateral ear wall resection
- Radiation therapy (48 Gy total dose): median DFI 40 months and 12-month survival rate 56%
EXTERNAL EAR TUMORS