title: Ultrastructure of a feline extraskeletal giant cell tumor (malignant fibrous histiocytoma).
abstract: A subcutaneous extraskeletal giant cell tumor (malignant fibrous histiocytoma) was excised repeatedly from a 9-year-old Domestic Shorthair cat. Ultrastructurally, the mass was composed of fibroblast-like, histiocyte-like, and multinucleated giant cells, and some undifferentiated cells and mononuclear cells intermediate between the fibroblast-like and histiocyte-like cells. Fibroblast-like cells were characterized by abundant well-developed rough endoplasmic reticulum, relatively smooth cytoplasmic membranes, few lysosomal structures, and finely granular chromatin. Histiocyte-like cells resembled immature macrophages. The cell membranes had many villous projections. Rough endoplasmic reticulum varied in quantity. Lysosomes were numerous. Multinucleated giant cells had characteristics of both the fibroblast-like and histiocyte-like cells. No viral particles were seen.
mesh_terms: D000818:Animals; D002371:Cat Diseases / Q000473:pathology*; D002415:Cats; D018219:Histiocytoma, Benign Fibrous / Q000648:ultrastructure / Q000662:veterinary*; D008297:Male; D012878:Skin Neoplasms / Q000648:ultrastructure / Q000662:veterinary*