[A case of intrathoracic chondrosarcoma of the rib head--comparison between MRI shadow and histopathological specimen].

A 71-year-old man was admitted our hospital because of mediastinal tumor. On chest X-ray, the mass was about 10 cm in diameter, contact with the right side of No. 3-5 vertebra and extended to the right thorax. After about 8 months, he felt anterior chest and back pain. Tumor was growing on chest X-ray and, on chest CT, linear and spotty calcification existed in it. On MRI, T1 weighted image, most part of tumor was low signal area but high area was also existed and it was parenchymatous hemorrhage. On T2 weighted image, tumor was high signal and irregular low area was calcification. Operation was performed and a hard tumor, measured 12 x 9 x 6 cm, originated from the 3rd-4th rib was resected. Histopathological diagnosis was chondrosarcoma. MRI was effective for the diagnosis of this case.