Duodenal leiomyosarcoma in a cat: Cytologic, pathologic, and immunohistochemical findings.

A 7-year-old mixed-breed neutered male cat was presented with a history of chronic vomiting with increased frequency in the last month, progressing to depression and profuse projectile vomiting. Abdominal ultrasonography revealed an area of marked segmental duodenal thickening associated with a nodule, and euthanasia was performed due to a poor prognosis. Grossly, at the postmortem examination, the wall of a duodenal segment was severely expanded by a nodule measuring 5.0 cm in diameter, resulting in marked luminal narrowing and obstruction. Smears were made by scraping the cut surface of the tumor during the postmortem examination. The smears were highly cellular and contained mesenchymal cells arranged individually or in large non-cohesive aggregates. Cells varied in morphology from spindle to round to stellate-shaped with marked anisocytosis and anisokaryosis. Numerous bi- and multinucleated neoplastic cells were observed. Histologic examination revealed a densely cellular neoplastic proliferation of mesenchymal cells that effaced the duodenal submucosa, muscularis externa, and serosa layers. Most cells were spindle-shaped; however, some tumor areas had numerous round cells and bi- and multinucleated neoplastic cells. Spindle cells showed variable cytoplasmic immunoreactivity for vimentin, smooth muscle actin, and desmin. Round, bi-, and multinucleated giant cells only had marked multifocal cytoplasmic immunoreactivity for vimentin. Neoplastic cells did not have immunoreactivity for cytokeratin, GFAP, S100, and CD117. A final diagnosis of duodenal leiomyosarcoma was made. This article reports the pathologic, cytologic, and immunohistochemical findings of this case and discusses the main differential diagnoses in cases of intestinal sarcomas in domestic animals.

Pathological and immunohistochemical aspects of acute megakaryoblastic leukaemia in a cat - Short communication.

An adult, mixed-breed, feline leukaemia virus (FeLV-) positive female cat was presented with mucosal jaundice and a history of anorexia and constipation for three days. Physical examination revealed splenomegaly, cachexia, and dehydration. Humane euthanasia was conducted, followed by postmortem examination. Grossly, the cat was icteric, and presented hepatomegaly with multifocal white spots and splenomegaly. Histologically, the bone marrow was nearly completely replaced by a proliferation of megakaryocytes and megakaryoblasts, and there was a proliferation of fibrous connective tissue. Similar neoplastic proliferation was observed infiltrating the liver, lymph nodes, spleen, kidney, skeletal muscle, and lungs. Immunohistochemistry was performed for von Willebrand Factor (VWF), CD79α, CD3, feline immunodeficiency virus, FeLV, and CD61. Marked cytoplasmic labelling was observed in the neoplastic cells for FeLV, VWF and CD61, corroborating the diagnosis of acute megakaryoblastic leukaemia.