Two cases of neoplasia of basal cell origin affecting the axillary region in anseriform species.

Neoplasms of the skin are occasionally seen in domestic birds but are uncommon in nondomestic birds. An 8-year-old male hooded merganser (Lophodytes cucullatus) was presented with bilateral axillary ulcerative lesions that improved but did not resolve with empiric antibiotic and antifungal therapy. Skin biopsies were taken, and bilateral feather folliculomas were diagnosed on histopathologic examination. The duck was euthanatized because of the poor prognosis. A 9-year-old Indian runner duck (Anas platyrhynchos) was presented with an ulcerative lesion, with pseudomembrane and serocellular crust affecting the axillary region. This mass was diagnosed as a basosquamous carcinoma. The mass was surgically excised, and no recurrence was observed. Feather folliculomas are usually considered benign neoplasms in domestic birds and may be primarily ulcerative, exudative, bilateral, and symmetric in location. Basosquamous carcinoma may have a similar gross appearance. It is unknown if the axillary region may be an area with increased incidence of neoplasia in birds. This appears to be the first report of feather folliculoma and basosquamous carcinoma in Anseriforme species. Feather folliculomas and other neoplasms, such as basosquamous carcinoma, should be considered as a differential diagnosis in ulcerative or proliferative skin lesions in birds.