KIT-positive gastrointestinal stromal tumor in a 22-year-old male chimpanzee (Pan troglodites).

Gastrointestinal stromal tumors (GIST), KIT-positive and KIT signaling driven or platelet-derived growth factor receptor alpha (PDGFRA) signaling driven mesenchymal tumors, are poorly known in nonhuman primates. Availability of KIT- and PDGFRA-inhibitor drug imatinib mesylate has greatly raised the interest for these tumors. At necropsy of a 22-year-old male chimpanzee, a round, firm 2-cm intramural tumor was incidentally found in the midbody of the stomach and diagnosed as a GIST. Histologically, the mass was composed of spindle to polygonal epithelioid cells arranged in short to intermediate-length, interlacing streams, bundles, and nodular whorls often separated by hyalinized eosinophilic matrix. The mitotic rate was a maximum 1/50 high-power field. Immunohistochemically, the tumor cells were diffusely positive for KIT and CD34, focally positive for alpha-smooth muscle actin, and negative for muscle specific actin, desmin, S-100 protein, synaptophysin, and glial fibrillary acidic protein. Because the majority of human GISTs have gain-of-function KIT or PDGFRA mutations, genomic sequences of KIT exons 9, 11, 13, and 17 and PDGFRA exons 12 and 18 from this chimpanzee GIST were polymerase chain reaction amplified and sequenced. However, no mutation was identified in the analyzed "mutational hot spots." This study is the first extensive histomorphologic, immunohistochemical, and molecular genetic analysis of a chimpanzee GIST. More cases of nonhuman primate GISTs should be analyzed to discover the clinicopathologic spectrum of GISTs in these species.

Surgical correction of severe vaginal introital stenosis in female baboons (Papio sp.) infected with simian agent 8.

Simian agent 8 (SA8) is a neurotropic, endemic alphaherpesvirus in Papio sp. Lesions associated with simian agent 8 infections usually involve the genitalia of sexually mature baboons. In females, secondary bacterial infections may lead to scarring of the vulva and perineum, with resulting vaginal obstruction. Affected baboons are poor breeders and often develop urinary tract infections due to retention of urine in the vagina. Reconstructive vaginal surgery was performed on seven baboons with vaginal obstruction. Four weeks before surgery, 50 mg of Depo-Provera was administered intramuscularly to each animal to arrest the estrous cycle, reduce swelling, and allow adequate surgical exposure of the vagina. Ventral and circular incisions were made around the constricted vagina. The peripheral skin was excised to break down the underlying connective tissue, allowing access to the vaginal mucosa. Healthy vaginal tissue was then opposed to the incised skin edges with 3-0 Vicryl in an interrupted pattern. Once healed, the vaginas remained patent, allowing normal mating and urination. Nine months after surgery, five baboons had healthy infants, and pregnancy was confirmed in the other two animals. The described procedure may allow female baboons previously infertile and at risk of urinary tract infections to be returned to a healthy reproductive state.