Osteosarcoma of the patella. A case report.

A 34-year-old woman complained of pain and swelling in the left patella. Because of roentgenogram showed hardly any destruction of the patella, she was not initially treated for a bone tumor. The clinical course followed the initial symptoms of a respiratory disorder with pulmonary metastatic foci. A bone tumor was first suspected after aspiration cytology of a lung tumor mass. A left patellectomy was performed to relieve the pain and confirm the diagnosis. The pain was relieved by the operation, but respiratory failure set in and progressed rapidly. The patient died three days later. Histologic examination showed that the tumor tissue consisted of atypical cells, spindle to polygonal in shape. The marrow space of the patella was predominantly occupied by neoplastic cartilaginous tissue. The pathologic diagnosis was primary chondroblastic osteosarcoma of the patella.