title: Spontaneous multicentric malignant schwannoma in a male Fischer 344 rat.
abstract: We describe here a multicentric spontaneous malignant schwannoma obtained from one male F344 rat, and this animal was the subject of a carcinogenicity study for which it was treated with diisodecyl phthalate. The animal of the control group not treated with diisodecyl phthalate showed dyspnea and severe lordosis. On the necropsy, two tan, firm, encapsulated masses were observed in the subcutis of the lumbosacral region and the left inguinal region of the abdominal cavity, respectively; the masses were 25 × 17 × 8 mm and 16 × 14 × 8 mm in size, respectively. Histologically, the tumor consisted of spindle and pleomorphic cells that grew in various patterns, that was, sweeping fascicles and herringbone and local organoid patterns. The pleomorphic neoplastic cells had more than two nuclei. Additionally, the diagnosis of malignant schwannoma was confirmed by the immune reactivity of the tumor cells for S-100 protein.
authors.affiliation: Korea Food and Drug Administration, Chungcheongbuk-do 363-951, Korea.
authors.forename: Bang Hyun
authors.initials: BH
authors.lastname: Kim
authors.forename: Wan Seob
authors.initials: WS
authors.lastname: Cho
authors.forename: Beom Seok
authors.initials: BS
authors.lastname: Han
keywords: F344 rat; Multicentric spontaneous malignant schwannoma; S-100 protein