Atypical manifestation of lung metastasis 17 years after initial diagnosis of low-grade central osteosarcoma

Multimodality therapy has greatly improved the prognosis of patients with localized osteosarcoma, over 50% of patients remaining free of disease for up to 5 years after treatment [1e4]. Most relapses, especially in the form of early pulmonary metastasis, usually occur within 2e3 years after treatment. Relapse after 5 years is uncommon and has been described only infrequently [1e7]. Low-grade central osteosarcoma is a rare subtype of osteosarcoma, accounting for 1e2% of all osteosarcomas [8,9]. Although its prognosis is excellent, with 90% overall survival at 5 years [8], some cases of late metastasis have been reported, and this may continue to impact survival even after 10 years [10]. Here we report a case of lung metastasis that occurred 17 years after initial treatment of low-grade central osteosarcoma of the distal femur. Radiologic evaluation revealed atypical pleural thickening with calcification, spreading inward along with the peripheral pulmonary vasculature. Since the presentation and radiologic manifestation of metastasis in this case were extremely unusual, and demographic data are an essential part of diagnosis, the