title: Malignant myopericytoma-like tumor in a Fischer rat.
abstract: Myopericytoma is a perivascular tumor that has been recently described in humans, but not in laboratory rodents. The authors encountered an intra-abdominal tumor resembling human malignant myopericytoma in a Fischer rat. Grossly, the tumor was found as two brown-colored masses located in the mesentery of rectum. Microscopically, the tumor was composed of oval to spindle-shaped cells, which were arranged in sheets around numerous thin-walled branching vessels and partly showed a concentric perivascular growth pattern. Mitoses were frequently seen, and the tumor cells showed a local invasion. Immunohistochemically, the tumor cells were strongly positive for alpha-smooth muscle actin and weakly positive for vimentin and desmin. Ultrastructurally, the tumor cells had dendritic processes, actin-like thin filaments with dense bodies, basement membranes, hemidesmosomes, and micropinocytotic vesicles. These findings suggest that the most appropriate term for diagnosis of the present case could be a malignant myopericytoma.
authors.affiliation: Laboratory of Pathology, Toxicology Division, The Institute of Environmental Toxicology, Uchimoriya-machi 4321, Joso-shi, Ibaraki, Japan. n.takahashi@iet.or.jp
authors.forename: Naofumi
authors.initials: N
authors.lastname: Takahashi
authors.forename: Toshinori
authors.initials: T
authors.lastname: Yoshida
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Takeuchi
authors.forename: Maki
authors.initials: M
authors.lastname: Kuwahara
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Nakashima
authors.forename: Yuko
authors.initials: Y
authors.lastname: Chiba
authors.forename: Takanori
authors.initials: T
authors.lastname: Harada
mesh_terms: D000008:Abdominal Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D000199:Actins / Q000378:metabolism; D000818:Animals; D003893:Desmin / Q000378:metabolism; D005260:Female; D007150:Immunohistochemistry; D008938:Mitosis; D047708:Myofibroma / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D009383:Neoplasms, Vascular Tissue / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D051381:Rats; D011916:Rats, Inbred F344; D014746:Vimentin / Q000378:metabolism
chemical_list: D000199:Actins; D003893:Desmin; D014746:Vimentin