Sclerosing pneumocytoma mixed with a columnar clear cell adenoma and a typical carcinoid: case report and review of literature.

Sclerosing pneumocytoma (SP) is a rare and benign tumor predominantly occurring in Asian women, easily misdiagnosed by imaging and pathologic frozen diagnosis during surgery because of its diverse histomorphology (4 structures, 2 types of cells). It may form multiple tumors. When SP is combined with carcinoid, adenoma, or other tumors (although rare), diagnosis is more complicated. SP mixed with carcinoid tumor is rare. At present, only 4 cases have been reported in English literature. Here, we report a case of sclerosing pneumocytoma combined not only with carcinoid, but also with clear cell adenoma of the lung. The patient was a 52-year-old female and CT found a nodule in the middle lobe of the right lung. SP was not excluded by intraoperative frozen section diagnosis. The above 3 components formed a 1.4 cm nodule. The related literature is reviewed to strengthen the understanding of SP, and aid clinicopathological diagnosis.