Small Animal Dermatology Q&A 01

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A 5-year-old male Norwegian elkhound dog with generalized confluent dermal masses is shown. The tumors are firm to fluctuant, well-circumscribed, dermal to subcutaneous masses varying in size from 0.5–>5.0 cm. Some of the lesions have visible pores opening onto the surface of the skin; the pores are filled with cutaneous plugs. The dog is otherwise healthy.

Question	Answer		Article
What is the most likely diagnosis, what treatment options are available, and what is the prognosis?	Keratoacanthoma (also called an intracutaneous cornifying epithelioma). This is a benign neoplasm that can be solitary or multiple. Norwegian elkhound and keeshond dogs are predisposed to the generalized form. Single lesions can be confused with cutaneous horns or epidermal cysts because they look similar. These lesions are differentiated by histological examination of tissue. Solitary keratoacanthomas can be treated by surgical excision, cryotherapy, electrotherapy, and observation without treatment. Multiple lesions are usually too numerous for surgical excision. Oral retinoids (isotretinoin 1–3 mg/kg PO q24h) have been successful in the treatment of multiple keratoacanthomas in some dogs. Treatment responses may take up to 3 months and, if effective, need lifelong administration. Considered benign proliferations of skin epithelium, these lesions are benign, non-invasive, and do not metastasize. Dogs with generalized lesions have a strong tendency to develop new tumors at other sites. The generalized form is believed to have a hereditary basis in dogs.		[[|Link to Article]]
What is this the origin of these tumors?	These tumors originate from the superficial epithelium between hair follicles although some may originate from adnexa.		[[|Link to Article]]
If this tumor were aspirated, what would a cytological examination be expected to find?	Cytologically, these tumors are characterized by keratin debris, rafts of keratinocytes, keratin bars, cholesterol crystals, and inflammatory cells if the mass has ruptured. These tumors can be difficult to differentiate from inclusion cysts.		[[|Link to Article]]