Extraskeletal osteosarcoma of the lung following treatment of primary small-cell lung carcinoma with chemoradiotherapy: A case report.

Primary pulmonary osteosarcoma is a rare entity, with only a few cases reported in the literature to date. Moreover, secondary extraskeletal osteosarcoma of the lung following chemoradiotherapy is extremely rare and, to the best of our knowledge, this is the first reported case. We herein present the case of an 80-year-old male patient with small-cell lung cancer (SCLC), who developed what it was initially considered as recurrence of the tumor after chemoradiotherapy. The patient eventually succumbed to the disease, and on autopsy it was discovered that the lung tumor was not in fact SCLC, but rather a secondary osteosarcoma. Osteosarcoma metastasis to the lung is very rare, but must be considered in the differential diagnosis when there is relapse following treatment for primary SCLC.