Osteosarcoma relapse as pleural metastasis.

Osteosarcoma is the most common primary bone tumor in children and young adults arising from primitive mesenchymal bone-forming cells. The lung is the most common site of metastasis of osteosarcoma. Here, we report a case of a 14-year-old male patient having osteosarcoma of tibia presenting to us for evaluation of left-sided pleural effusion after 4 years of mid-thigh amputation. Contrast-enhanced computed tomography thorax revealed a large, heterogeneous, calcified mass (+277 H.U) at left upper and middle lobe along with massive left-sided pleural effusion. Thoracoscopy revealed a lung metastasis in the right upper and middle lobe along with 2-cm diameter mass found on the surface of parietal pleura. Lung tumor was resected and biopsy of the pleural mass was carried out. Histopathological examination from both the masses was suggestive of metastatic osteosarcoma. The case underlines the importance of performing thoracoscopy in patients of osteosarcoma who recur with lung metastasis.