A case report of a spontaneous gastrointestinal stromal tumor (GIST) occurring in a F344 rat.
We report a case of gastrointestinal stromal tumor (GIST) that developed in a male F344 rat at week 101 of an experiment in a carcinogenicity study. Macroscopically, the primary tumor, which measured 1 cm in diameter, involved the submucosal tissue of the forestomach at the lesser curvature extending to the glandular stomach and esophagus. Histopathologically, the tumor was composed of neoplastic cells with small- to medium-sized spindle-shaped single nuclei and fibrillary cytoplasm lacking distinct cell borders. It invaded extensively into the tunica muscularis and subserosa, further extending to the lamina propria mucosa and serosal surface. A few densely proliferating portions showed a tendency to storiform pattern. Metastatic tumor nodules were found in the liver, spleen, and femur bone marrow, with multiple nodules, up to 1 cm in diameter, apparent in the liver. Immunohistochemically, diffuse, but weak cytoplasmic immunoreactivity for KIT was evident, and most neoplastic cells also exhibited strong immunoreactivity for a -smooth muscle actin and vimentin. Sparse nuclear S-100-immunoreactive cells were further observed, but none of neoplastic cells were immunoreactive for CD34, caldesmon, desmin, cytokeratin, or synaptophysin. Collectively, these features meet the criteria for a GIST, with limited potential for differentiation to smooth muscle and neural cells.
Division of Pathology, National Institute of Health Sciences, Tokyo 158-8501, Japan.
Hitoshi
H
Fujimoto
Makoto
M
Shibutani
Keiko
K
Kuroiwa
Kaoru
K
Inoue
Gye-Hyeong
GH
Woo
Mami
M
U
Masao
M
Hirose
D000199:Actins / Q000032:analysis; D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis; D005770:Gastrointestinal Neoplasms / Q000737:chemistry / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D046152:Gastrointestinal Stromal Tumors / Q000737:chemistry / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D007150:Immunohistochemistry; D008297:Male; D009362:Neoplasm Metastasis; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis; D051381:Rats; D011916:Rats, Inbred F344; D012376:Rodent Diseases / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D009418:S100 Proteins / Q000032:analysis; D014746:Vimentin / Q000032:analysis
D000199:Actins; D018952:Antigens, CD34; D019009:Proto-Oncogene Proteins c-kit; D009418:S100 Proteins; D014746:Vimentin; C498862:Acta2 protein, rat