LOCALIZED RETROPERITONEAL FIBROMATOSIS CAUSING INTESTINAL-OBSTRUCTIONIN A CYNOMOLGUS MONKEY (MACACA-FASCICULARIS)

Gross examination of a 24-month-old, male cynomolgus monkey (Macaca fa scicularis) revealed obstruction of the ileum by a mass that entrapped and compressed the ileocecal junction. The mass was well circumscribe d, firm, and white on cut surface. Histologically, the mass consisted of spindle-shaped cells arranged in interweaving bundles or as narrow cords and individual cells widely separated by dense collagen. A diagn osis of localized retroperitoneal fibromatosis was made based on the c haracteristic gross and microscopic findings and isolation of type D s imian retrovirus, serotype-2, from spleen and mesenteric lymph node. M onkeys with localized retroperitoneal fibromatosis generally exhibit s igns only of a palpable mass at the ileocecal junction and/or nonspeci fic diarrhea. This case represents an unusual presentation of localize d retroperitoneal fibromatosis in which the lesion produced intestinal obstruction and death.