Pleomorphic iridociliary adenocarcinoma with metastasis to the cervical lymph node in a chinchilla (Chinchilla lanigera)

A tumor had formed in the right eye of a 14-year-old male chinchilla. The black-and-white-colored tumor occupied the entire eye except for the lens and had invaded extensively inside the orbit. Histologically, round, spindle- to polygonal-shaped tumor cells had proliferated in a solid-sheet arrangement. The tumor cells exhibited polymorphic nuclei ranging from round- to polygonal-shaped, as well as abundant cytoplasm, which occasionally contained melanin granules. In some areas, several cells were surrounded by the basal lamina. Additionally, the tumor showed cervical lymph-node metastasis. Upon immunostaining, the tumor cells were positive for epithelial markers (cytokeratin AE1/AE3, 8/18, and 20), S100, and vimentin. Consequently, we diagnosed primary pleomorphic iridociliary adenocarcinoma with lymph-node metastasis. This is the first report of iridociliary adenocarcinoma in chinchillas.