[Analysis of clinicopathological features of clear cell tumor of the lung]

Objective: To analyze the clinicopathological features of clear cell tumor of the lung (CCTL). Methods: A total of 9 cases were collected from August 2008 to August 2019 in the Department of Pathology of the First Medical Center of PLA General Hospital and Hainan Hospital of PLA General Hospital. Their clinical data, pathological characteristics, immunohistochemical staining and special staining results were summarized and analyzed. Results: There were 3 males and 6 females, aged from 28 to 70 years (average 52.2 years). All tumors were located in the peripheral part of the lung, and were solitary in 8 cases, and multiple (24 nodules) in 1 case. The lesion was round or oval, with clear boundary. The diameter of the nodule was 0.5-5.5 cm. Histologically, the tumor cells were oval, short fusiform or polygonal, with obvious nucleoli. The tumor cells were mostly distributed in sheet around thin-walled vessels, and there was hyaline degeneration around the blood vessels. Neither necrosis nor mitosis could be seen. Immunohistochemical staining showed tumor cells were diffusely positive for Vimentin, and CD34, Melan-A, specific monoclonal antibody against melanoma (HMB45) and S-100 were positive with different degrees. Broad spectrum cytokeratin (CK), epithelial membrane antigen (EMA), smooth muscle actin (SMA), desmin, CD10, paired box gene 8 (PAX-8) or myomodulatory protein (Myo-D1) were all negative. The positive index of the proliferating cell nuclear antigen (Ki-67) was low. Schiff dyeing with periodate (PAS) staining was positive, PAS staining of glycogen digested by amylase (d-PAS) staining was negative. All the tumors in the nine cases were resected and patients were followed up for 5-137 months. Except 1 case was lost for follow-up, the other 8 cases survived without recurrence or metastasis of the disease. Conclusions: CCTL is a rare benign tumor, most of which are single, few of which can be multiple; histopathological characteristics and immunohistochemical staining are helpful for diagnosis and differentiated diagnosis. After complete resection, the prognosis was good. However, when histological features indicating malignancy, intense follow-up should be considered.