[Clear cell tumor of the lung: report of seven cases and literature review].

Objective: To study the clinical characteristics, chest imaging, pathology, diagnosis and treatment of clear cell tumor of the lung (CCTL).

Methods: Seven cases of CCTL diagnosed from January 2000 to December 2010 in our hospital, and 38 cases from literatures published in mainland of China, were retrospectively analyzed.

Results: The age of the patients was (44 ± 18) years, with equal sex distribution. In most of the patients, the lesions were incidentally found during routine examinations. Chest roentgenogram or CT scan showed a homogenous, rounded opacity (solitary nodule) of (3.2 ± 1.4) cm in diameter. Contrast-enhanced CT scans revealed a sign of intense enhancement because of these tumors were highly vascular, containing capillaries and sinusoidal vessels in some patients. Pathologic examination showed rounded and oval tumor cells with abundant clear cytoplasm, distinct cell borders, and cytoplasm rich in periodic acid Schiff-positive glycogen granules. Immunohistochemically, CCTL expressed melanocytic and myogenic markers, such as human melanoma black-45 (HMB-45), HMSA-1 and actin. But its epithelial markers were negative. Resection via operation was the only effective method till now.

Conclusions: CCTL is a rare benign tumor with special features of clinical characteristics, radiology and pathology. The diagnosis is based on distinct pathologic characteristics. Earlier operation with long term follow-up is recommended.