title: A neuroendocrine carcinoma of undetermined origin in a dog.
abstract: In this report, we describe a case of neuroendocrine carcinoma of undetermined origin in a dog. Necropsy revealed scattered small neoplastic nodules in the bilateral lungs and a small nodule in the parapancreatic lymph node. Histopathologically, both pulmonary and lymph nodal nodules showed a similar histologic pattern, with neoplastic cells being arranged in diffusely proliferating sheet-like cellular nests separated by variable amounts of fibrous septa, sometimes forming rosettes and duct-like structures. Scattered small necrotic foci and invasion to fibrous septa were typically observed. Neoplastic cells showed round to oval-shaped nuclei with prominent nucleoli and abundant eosinophilic cytoplasm that were positive for Grimelius' silver impregnation staining and immunostaining with cytokeratin, synaptophysin, vasoactive intestinal peptide and chromogranin A, indicative of the development of a neuroendocrine carcinoma. However, judging from the distribution of tumors lacking the portion suggestive of the primary site in any organ examined, as well as no further indication of differentiation potential of neoplastic cells, this tumor has so far been diagnosed as neuroendocrine carcinoma of undetermined origin.
authors.affiliation: Laboratory of Veterinary Pathology, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Kuwata
authors.forename: Makoto
authors.initials: M
authors.lastname: Shibutani
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kemmochi
authors.forename: Eriko
authors.initials: E
authors.lastname: Taniai
authors.forename: Reiko
authors.initials: R
authors.lastname: Morita
authors.forename: Bunichiro
authors.initials: B
authors.lastname: Ogawa
authors.forename: Kunitoshi
authors.initials: K
authors.lastname: Mitsumori