A case of the large retroperitoneal solitary fibrous tumor

A rare autopsy case of the extremely large retroperitoneal solitary fibrous tumor is reported. A 52-year-old female with a huge abdominal distention was found dead at home. She showed remarkable emaciation. The autopsy revealed a huge retroperitoneal tumor weighing 11.9 kg (36 × 30 × 20 cm in size), which occupied the entire intraperitoneal cavity. Histologically, the tumor consisted of spindle parenchymal cells with fibrous tissues. Immunohistochemically, CD34 was positively stained, whereas S-100, smooth muscle actin, and factor VIII were negative. Her cause of death was diagnosed as emaciation due to the compression of the entire intestine by the tumor. This is a rare case of the extremely large retroperitoneal solitary fibrous tumor, which caused the occasional intestinal obstruction. This disease should be considered in the differential diagnosis of retroperitoneal large tumors that cause accidental deaths in forensic autopsies.