[Clinicopathological analysis of lung metastatic tumor]

Objective: To investigate the clinicopathological features and differential diagnosis of metastatic tumors in the lung. Methods: The clinicopathological data of 226 metastatic tumors in the lung were collected at Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, from January 2014 to December 2018, and the pathomorphological characteristics were analyzed. Results: There were 84 males and 142 females, with an age range from 13 to 77 years. There were 122 patients with multiple pulmonary nodules and 104 patients with solitary pulmonary nodule. The tumors of the highest frequencies were colorectal cancer (n=59), followed by trophoblast tumor (n=44), kidney cancer (n=31), breast cancer (n=20), cervix cancer (n=14), and urinary urothelium cancer (n=8). The time from the diagnosis of primary tumors to metastasis and the status of surgical treatment varied by tumor origin. The morphology of metastatic lung tumors overlapped with that of the primary tumors to some extent. The relative specific morphological characteristics and the presence of carcinoma in situ surrounding the tumors should be carefully searched for to confirm the tumor origin. The metastatic tumors of the lung had morphological characteristics, immunohistochemical TTF1 (-) and tumor of various sources, while the primary tumor differentiation had relatively specific antibodies: colorectal cancer CK20 (+), CDX2 (+), CK7 (-); malignant trophoblastic tumor, HCG (+); renal clear cell carcinoma CD10 (+), vimentin (+), CK7 (-); breast cancer, GATA3 and ER (+); cervical cancer, p16 (+); urothelial carcinoma, CK20, p63 and GATA3 (+). Conclusions: There is overlap between pulmonary metastatic tumor and primary tumor in morphology. Therefore, the diagnosis should be made by combining clinical history, pathological morphology and immunophenotypic characteristics.