title: Feline mammary sarcoma composed of cells resembling myofibroblasts.
abstract: A recurrent mammary sarcoma from an 11-year-old, female domestic cat was studied by light and electron microscopy and immunohistochemistry. The tumor consisted of interlacing bands of spindle cells with elongated blunt-ended nuclei and variable amounts of stroma. Multinucleated tumor giant cells and mitoses were common. Ultrastructurally, tumor cells had abundant rough endoplasmic reticulum with dilated cisternae, a prominent Golgi complex, frequent mitochondria, bundles of intracytoplasmic filaments with focal densities, and discontinuous basal lamina-like material and cell junctions. These findings suggest that myofibroblast-like cells were the predominant type of tumor cell. Failure to demonstrate immunoreactivity for cytokeratins attested to the non-epithelial origin of these neoplastic cells. Uniform immunoreactivity with anti-vimentin antibodies and specific labelling of some tumor cells with antiserum to actin are compatible with an origin of this tumor from modified fibroblasts (i.e., myofibroblast-like cells). Tumors composed largely of myofibroblasts may be unique and warrant separate classification from other types of fibroblastic tumors in animals.
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000473:pathology*; D002415:Cats; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000648:ultrastructure; D008321:Mammary Glands, Animal / Q000473:pathology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D012509:Sarcoma / Q000473:pathology / Q000648:ultrastructure / Q000662:veterinary*