Large retroperitoneal low-grade extraskeletal osteosarcoma.

Low-grade extraskeletal osteosarcoma is an extremely rare neoplasm with only nine cases reported in the literature, in which only one case involved the retroperitoneum. Tendency to dedifferentiate as well as recur with high-grade variant is known and management principles are not well defined, necessitating a continuous review of literature. We report management of the largest such retroperitoneal tumour (18.0 cm × 18.3 cm × 17.8 cm) in a 38-year-old man, which was treated with surgery followed by six cycles of cisplatin (90 mg/m(2) days 1 and 2) and doxorubicin (75 mg/m(2) day 3), cycled every 3 weeks (with granulocyte colony stimulating factor support as necessary). The patient is disease free after 3 years of follow-up.