Metastatic peritoneal sarcomatosis from radiation-induced osteosarcoma in a patient with previously treated pelvic Ewing’s sarcoma: Report of a case

Metastatic peritoneal sarcomatosis most commonly occurs from primary soft tissue sarcomas arising either within the abdomen or extremities. Metastatic peritoneal sarcomatosis from an osteosarcoma is extremely rare; only six cases have previously been reported. We report the first case of metastatic peritoneal sarcomatosis originating from radiation-induced osteoblastic osteosarcoma in a 22-year-old woman who had previously been treated for pelvic Ewing’s sarcoma. Abdominal computed tomography, bone scintigraphy and FDG PET/CT demonstrated extensive finely nodular disseminated peritoneal lesions. Histopathologic examination of these peritoneal lesions revealed osteosarcomatosis. In summary, we describe an unusual case of metastatic peritoneal sar comatosis from secondary osteosarcoma arising in a previously irradiated pelvic Ewing’s sarcoma.