Solitary Pulmonary Capillary Hemangioma of Adult Cases: Clinicopathologic Characteristics as an Unrecognized Entity.

Solitary pulmonary capillary hemangioma (SPCH) is a rare disease, first described about autopsy cases in 2000 and about surgically resected cases in 2006. To date, only 9 surgically resected cases have been published in English. Here, we report 7 original cases with surgery (median age, 54 y; 4 females, 2 never-smokers). All patients were asymptomatic, and all nodules were detected by computed tomography (CT). The median (range) size of nodule was 11 (8 to 16) mm. Six of 7 cases showed the part-solid nodule appearance and 1 showed pure ground-glass nodule appearance in CT findings. The growth speed was very slow. No abnormal uptake of fluorine-18 fluorodeoxyglucose was observed in systemic positron-emission CT in all 3 cases we examined. No patients died from SPCH. Histologically, SPCH manifested as a solitary lesion composed of densely proliferating and dilated capillaries without cytologic atypia within the alveolar septa. In addition, capillaries of SPCH spread into the vascular lumen and involved the walls of bronchioles with protrusion into the lumen. Immunohistochemically, capillaries of SPCH uniformly expressed endothelial markers, such as CD31, CD34, and Factor VIII; and α-smooth muscle actin positive cells were also observed. To be accurately diagnosed, especially in intraoperative frozen sections, SPCH should be conceived as an entity that presents as a solitary nodule in CT. We propose that SPCH is an unrecognized benign capillary proliferative disease.