Search

Abstract A 7‐year‐old intact Netherlands Dwarf rabbit with bloody discharge from the vulva underwent ovariohysterectomy. Grossly, both sides of the uterus were enlarged. Histologically, the tumour had formed protruded from the myometrial wall toward the serosa and was composed of irregular small capillaries with irregularly shaped structures and bundled proliferation of spindle‐shaped cells. No tumour cells infiltrated the endometrium. The tumour cells were positive for CD31, and histological and immunohistochemical staining confirmed the diagnosis of haemangiosarcoma. Vascular tumours in the uterus of animals are uncommon, and only one case has been reported in the uterus of rabbits.

A 12-year-old female Himalayan cat underwent an ovariohysterectomy to remove an intra-abdominal mass. Histologic examination using immunohistochemical staining revealed that the mass was comprised of epithelial and mesenchymal components. Within the lesion, multinucleated giant cells (MGCs) were observed diffusely. MGCs were positive for vimentin and Iba-1 and negative for cytokeratin AE1/AE3 and CD204. In addition, MGCs were negative for Ki‐67, indicating nonneoplastic cells. Osteoclast-like MGC (OLMGC) phenotype with tartrateresistant acid phosphatase positivity was also seen. These findings suggested that the uterine tumor was carcinosarcoma with OLMGCs. Uterine tumors in humans, such as leiomyosarcoma and carcinosarcoma, with OLMGC infiltration, are well-known pathologic entities; however, they are rare in animals and to our knowledge, have not been previously reported in cats. [ABSTRACT FROM AUTHOR]