Takahashi Naofumi, Yoshida Toshinori, Takeuchi Yukiko, Kuwahara Maki, Nakashima Nobuaki, Chiba Yuko, Harada Takanori
Laboratory of Pathology, Toxicology Division, The Institute of Environmental Toxicology, Uchimoriya-machi 4321, Joso-shi, Ibaraki, Japan.
Toxicol Pathol. 2008 Jul;36(5):738-42. doi: 10.1177/0192623308320804. Epub 2008 Jul 22.
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.
