Shortly after Dr Folkman’s publication, the first case of familial pulmonary capillary hemangiomatosis (PCH) was described, and another family was described in 2011.2,3 PCH is a rare disorder that was first reported in 1978, with only seven nonrelated cases having been reported by 1998 and a little more than 100 by 2011.2,4,5 The diagnostic histologic feature is the proliferation of capillaries in the pulmonary interstitium.5 However, another essential feature is evidence of invasion by the capillaries into one or more of the pulmonary veins and arteries, alveolar walls and alveolar space, intralobular fibrous septa, and bronchi. Affected areas tend to have a patchy distribution within the lung, and reticulonodular infiltrates may be seen on radiography. Less frequently, the capillaries invade pericardium, pleura, and mediastinal lymph nodes. The first case report described endothelial nuclear pleomorphism and hyperchromasia and suggested that PCH was a form of endothelial neoplasia.4 The clinical picture varies depending on the affected lung structures; therefore, PCH may mimic idiopathic pulmonary arterial hypertension, pulmonary veno-occlusive disease, or atypical interstitial lung disease and may result in a misdiagnosis as airways disease. Once symptoms appear, the course usually is fulminant and fatal. Ultimately, the diagnosis is made by lung biopsy or at lung transplantation or autopsy. Case reports appeared suggesting therapeutic success with interferon-α and doxycycline, but consistently effective therapy remained elusive.6,7 It is interesting to note that both reported therapies affect angiogenesis. However, the cause of PCH remained a mystery.