Microscopic sclerosing hemangioma diagnosed by histopathological examination after lung cancer surgery.

A 44-year-old woman underwent surgery for lung cancer. Although preoperative computed tomography did not reveal a tiny nodule, pathological examination of the background lung showed that type II pneumocyte-like tumor cells grew papillary in an area of approximately 2.3 × 1.2 mm. This lesion exhibited hemorrhage, hemosiderosis, calcification, and varying degrees of fibrosis, leading to the diagnosis of sclerosing hemangioma. This is the first reported case of microscopic sclerosing hemangioma undetectable by chest computed tomography.