Amyloid-producing odontogenic tumour (calcifying epithelial odontogenic tumour) in the mandible of a Bengal tiger (Panthera tigris tigris).

A 13-year-old male tiger (Panthera tigris tigris) had a marked mandibular swelling noticed 12 months earlier and associated with progressive anorexia and weight loss. Radiological and post-mortem examination revealed a mass (13x15 cm) which was firm and poorly defined, with destruction of the adjacent bone tissue. Histologically, the mass was poorly demarcated, with infiltrative growth, and composed of nests, cords and islands of epithelial cells with characteristic basal cell features. Also observed were extensive squamous metaplasia, ghost cells, stellate reticulum, and fibroblastic connective tissue stroma containing inflammatory cells. A prominent feature of this tumour consisted of abundant nodular deposits of congophilic amyloid-like material with partial mineralization (Liesegang rings). Immunohistochemically, the neoplastic cells and the amyloid-like material were positive for pancytokeratin and negative for vimentin. The findings supported the diagnosis of an amyloid-producing odontogenic tumour (APOT), also known as calcifying epithelial odontogenic tumour in man and animals.