Two cases of clear cell tumor of the lung

We report two cases of benign clear cell tumor of the lung, which were found as well-circumscribed lesions on chest X-ray films without any symptoms, and removed surgically. Light microscopy showed proliferation of clear cells filled with glycogen in both cases. Immunohistochemical examination performed in a case suggested that the tumor cells might be associated to a derivation from neural and/or smooth muscle cells, because of positive staining for NSE and SMA. In another case, the tumor formed a necrotic cavity, which could be detected by the preoperative MRI examination. This report might introduce a note of caution for the pathologic and radiographic diversity of this disease.