Osteosarcoma presenting as an abdominal mass

A 29 year old woman was referred to a general surgeon by her GP with a 4 week history of pain in the left thigh, Examination revealed a large mass in the left iliac fossa, this was confirmed by ultrasound, A laparotomy was performed. A transperitoneal biopsy of the mass was reported as an osteosarcoma, The patient was referred to the Birmingham Bone Tumour Service, where CT scanning showed involvement of the sacrum and left ilium (Fig, 1), The patient was fully staged and had no obvious metastases. She was treated with chemotherapy followed by resection of the tumour through a transgluteal approach and fibula strut grafting (Fig. 2), At the time of the operation a small nodule was noticed on the pelvic floor and was biopsied, Histology showed osteosarcoma and this was clearly a "seed" implanted at the time of biopsy. Four months later the patient was admitted as an emergency complaining of abdominal distension. MRI showed an intra-abdominal mass which was not attached to bone and which was displacing bowel (Fig. 3). At laparotomy a large necrotic neoplasm with cystic and haemorrhagic areas was found consistent with osteosarcoma, The patient died of abdominal metastases 14 months following diagnosis.