An accidental finding of a retroperitoneal desmoid tumor: case report and review of the literature.

Retroperitoneal desmoid-type fibromatosis is a rare benign mesenchymal neoplasm that develops as a result of fibroblastic proliferation within the musculoaponeurotic stroma. The authors present the case of a 41-year-old male patient who was referred for a retroperitoneal neoplasm. A mesenteric mass core biopsy was done, and it revealed a low-grade spindle cell lesion consistent with desmoid fibromatosis.