Adenosquamous Carcinoma with Cilium Formation, Mucin Production and Keratinization in the Nasal Cavity of a Red Fox (Vulpes vulpes schrencki)

SummaryA diagnosis of adenosquamous carcinoma was made in an 11-year-old red fox. The animal showed emaciation and purulent nasal discharge. Necropsy revealed diffuse thickening of the nasal mucosa and tumours on the soft palate, and there was an oronasal fistula contiguous with the tumours. The nasal and oral lesions were composed of adenocarcinomatous cells and squamous cells, the latter predominating in the oral lesions. The marrow of the palatine bone also contained neoplastic tissue, which consisted of cysts and keratin masses surrounded by well-differentiated squamous cells. Although inconspicuous in the oral cavity and marrow, ciliated cells with or without mucin were observed in the adenocarcinomatous and cystic elements. Neoplastic basal cells and less-differentiated adenocarcinoma cells, which were identifiable by immunolabelling for cytokeratin 5 (CK5) and CK18, were considered to be pluripotential. These cells, which lined tubular structures, were distinct from intermediate cells in mucoepidermoid carcinoma, which can differentiate into squamous and mucin-producing cells but have a nondescript appearance.