Thymic carcinoma with neuroendocrine differentiation in a calf

A neuroendocrine carcinoma originating in the thymus was found in a 7-month -old, castrated male, Japanese Black calf. The neoplasm consisted largely o f very primitive cells, characterized by the paucity of cytoplasmic organel les, but a few cells were immunoreactive for somatostatin or neurofilaments . The expression of both cytokeratin and neurofilament protein was a featur e of neuroendocrine differentiation. This neoplasm considered to be a tumor of a thymic stem cell, with little but indubitable evidence of differentia tion into somatostatin-producing cells.