OBJECTIVETo investigate the clinicopathologic features of pulmonary capillary hemangiomatosis (PCH).

METHODSThe clinical and pathologic profiles of 2 PCH cases were evaluated. Immunohistochemical study (EnVision method) was performed on fixed tissues. The biologic behavior was analyzed with follow-up data.

RESULTSThe main presenting symptom was dyspnea. Chest radiography of the two cases depicted diffuse, ground-glass nodules, accompanied by enlarged central pulmonary arteries. Microscopically, the most distinctive feature was proliferation of capillary channels within pulmonary interstitium and alveolar walls, accompanied by muscularization of arterioles. Immunohistochemical study showed an abundance of mast cells in the lesion, and staining for platelet-derived growth factor receptor-beta (PDGFR-β) localized to vascular smooth muscles surrounding the proliferating capillaries and the mast cells. The index of Ki-67 was less than 1 percent and the p53 was negative.

CONCLUSIONSPCH is a rare vascular proliferative disease of yang patients. Increased number of mast cell and the up-regulation of PDGFR-β may suggest mechanism for PCH. The clinical and radiologic diagnosis of PCH can be very difficult, and the histological examination is regarded as the most reliable means to establish the diagnosis. Pathologists should improve their knowledge on PCH.