Benign clear-cell tumor ("sugar" tumor) of the lung: a case report and review of the literature.

Benign clear-cell tumor of the lung is a rare, distinctive, primary neoplasm with unique histologic and electron microscopic features which may resemble metastatic renal-cell carcinoma. This tumor typically presents as an asymptomatic, peripheral, sharply rounded mass in the lung. Clinical recognition can prevent an unnecessary search for a primary malignant source.