Pulmonary capillary hemangiomatosis

Pulmonary capillary hemangiomatosis (PCH) is an extremely rare vascular disorder characterized by the uncontrolled proliferation of thin-walled capillaries within the lungs. These abnormal capillaries infiltrate the walls of pulmonary veins, arteries, bronchioles, and interlobular septa, leading to progressive obstruction of pulmonary blood flow. PCH is now considered to be closely related to, or a histological variant of, pulmonary veno-occlusive disease (PVOD), and both conditions are classified together under the broader category of pulmonary veno-occlusive disease and/or pulmonary capillary hemangiomatosis (PVOD/PCH). The primary body system affected is the pulmonary vasculature, which leads to pulmonary hypertension and progressive right heart failure. Key symptoms include progressive exertional dyspnea (shortness of breath with activity), fatigue, hemoptysis (coughing up blood), and signs of pulmonary hypertension such as chest pain, syncope (fainting), and peripheral edema. Chest imaging may reveal diffuse bilateral ground-glass opacities, septal thickening, and pleural effusions. The disease can be difficult to distinguish from other forms of pulmonary arterial hypertension, and definitive diagnosis often requires histological examination of lung tissue. The prognosis of PCH is generally poor. Standard pulmonary arterial hypertension vasodilator therapies may worsen the condition by causing pulmonary edema, as they can increase blood flow into an obstructed venous bed. Lung transplantation remains the only definitive treatment option. Some case reports have described partial responses to interferon-alpha or chemotherapeutic agents, but no established medical therapy exists. Biallelic mutations in the EIF2AK4 gene have been identified in heritable forms of PVOD/PCH, providing a molecular basis for genetic testing and counseling in affected families.

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