Pulmonary sclerosing pneumocytoma presenting as slow-growing multiple nodules over a long period.

Pulmonary sclerosing pneumocytoma is an uncommon slow-growing benign tumor that usually occurs in middle-aged women and generally presents as a solitary well-defined nodule. An 18-year-old woman was incidentally detected to have multiple lung nodules on chest radiography that slowly increased in size over a period of 7 years. Computed tomography images showed multiple well-defined nodules surrounded by numerous smaller nodules with a maximum diameter of 3 cm in the left lung. A percutaneous core needle biopsy was performed, but malignancy could not be excluded because of the high proportion of papillary structures. A video-assisted partial wedge resection was performed and the pathologic diagnosis was pulmonary sclerosing pneumocytoma. Pulmonary sclerosing pneumocytoma presenting as multiple lung nodules is a rare but very important condition to include in the differential diagnosis of multiple lung nodules. There is a possibility of misdiagnosis of another type of tumor or malignancy on preoperative biopsy. We should be aware not only of the clinical, radiologic, and pathologic features of pulmonary sclerosing pneumocytoma but also of the potential pitfalls in its diagnosis and management.