Unusual abdominal metastases in osteosarcoma

Abstract

Intraabdominal metastases in the setting of osteosarcoma are very rare. We describe a case of a 17-year-old boy with high-grade right distal femur osteosarcoma who two years after diagnosis developed extensive intra abdominal metastases involving the omentum, peritoneum, bowel serosa, psoas muscles and abdominal soft tissue. Awareness of and surveillance for unusual patterns of metastasis may allow for earlier detection, intervention, and palliative care decision-making, which may affect survival and quality of life. This report underlines the need for prospective studies evaluating surveillance guidelines for patients after medical and surgical management of osteosarcoma, especially in cases complicated by pulmonary metastases.

Keywords: Pediatric osteosarcoma; extra-pulmonary metastases; extra-pulmonary recurrence; surveillance imaging.

Fig 1

Conventional radiographs of the right knee demonstrate a blastic lesion in the distal femoral meta-diaphysis.

Fig. 2

CT imaging of the chest, abdomen, and pelvis demonstrates omental calcification/ossification, extensive peritoneal calcification/ossification, and calcified/ossified psoas masses. Numerous calcified/ossified soft tissue nodules and sclerotic bone metastasis in the spine are evident.

Fig. 3

A bone scan performed 15 months after diagnosis showed no evidence of extrapulmonary metastasis. A subsequent bone scan, taken 2-1/2 years post diagnosis, demonstrates new ^99mTc-MDP uptake in multifocal bone metastases and omental metastasis (black arrow), as well as serosal calcification involving the sigmoid colon (white arrows) and soft tissue calcification in the left thigh (curved black arrow).