Squamous cell carcinoma is commonly associated with solar keratosis, especially in white/sparsely-haired locations in cats. Lesions are common on the ears, nose, lips, and frontal ridges. There is no breed or sex predilection.
Surgical excision is the treatment of choice, but advanced tumors may have invaded surrounding bony structures making surgical excision impossible. Adjunctive radiation therapy may be considered. These lesions can be prevented by minimizing UV radiation exposure in at-risk animals.
Ceruminous gland carcinoma can range in appearance from fibrotic dermal nodules to ulcerated plaques. It would not occur on the tips of the pinnae and would not be bilateral.
Frostbite would not occur in a cat that lives indoors. It can cause a similar presentation.
Pemphigus foliaceus is an immune-mediated disorder of the skin. Look for erosions, ulcerations, and thick encrustations of the mucocutaneous junctions and skin.
Feline proliferative and necrotizing otitis externa is rare and occurs on the inner aspect of the pinnae, the ear canal, or the external aural orifice (not the tips). It has an unknown etiology.
Image courtesy of Caroldermoid.
