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Multiple Cystic Pulmonary Metastases from Osteosarcoma

Accessible online at: www.karger.com/res A 25-year-old man was admitted to hospital with a mass in the right thigh. Histopathological examination of the biopsy specimen from the mass revealed osteosarcoma (OS). The patient underwent neoadjuvant chemotherapy, and resection of the right lower extremity and reconstructive surgical treatment were performed. An adjuvant chemotherapy was begun. Chest radiography and computed tomography (CT) before operation and at 3to 6-month intervals during the year following surgery were normal. One year after surgery, the patient developed a productive cough with dyspnea and hemoptysis. Chest radiography showed widespread cystic and nodular opacities in both lobes of the lung (fig. 1). CT of the lung revealed multiple lung cysts of varying size located both centrally and subpleurally in both lungs with a ground-glass appearance in the lower lobes. The cyst walls were smooth and thin (fig. 2). Fiberoptic bronchoscopy revealed no endobronchial lesion. Bronchial brush cytology showed cells with atypical nuclear features, suspicious of malignancy. A CT-guided fine-needle biopsy was performed. Histopathological examination of the core biopsy and smear showed highly anaplastic nuclei of osteoblast-like and spindle cells with atypical mitotic figures. There were many multinucleated osteoclast-like giant cells and neoplastic osteoid matrix between the tumor cells which were consistent with OS (fig. 3). Pulmonary metastases of OS usually present as solitary or multiple pulmonary nodules, and the frequency of such nodules was found to be 47.7% in our previous study [1]. In that study, we showed that patients with sarcomas in the extremities also have different radiologic appearances such as pulmonary mass, pleural effusion, hilar lymphadenopathy and pneumothorax [1]. In the present case, the possible mechanism for the sudden development of malignant cysts and nodules is indicated by the presence of microscopic metastases. Lung cysts were probably caused by progressive distension and rupture of the alveolar air sacs secondary to a ball-valve effect of tumor infiltration of the terminal bronchials [2]. This presentation emphasizes that lung metastases may present as multiple cystic lesions rather than radiological appearances such as nodules, mass or pneumothorax in patients with OS.