Pulmonary Capillary Hemangiomatosis
Pulmonary capillary hemangiomatosis (PCH) is a rare disorder of alveolar capillary proliferation that clinically masquerades as idiopathic pulmonary arterial hypertension, or pulmonary venoocclusive disease (PVOD). The distinction of PCH or PVOD from idiopathic pulmonary arterial hypertension is important, because pulmonary vasodilators may be deleterious in patients with PCH and PVOD. Imaging with high-resolution computed tomography may alert to the possibility of these disorders,1 but a lung biopsy is required for the confirmation of the diagnosis. Lung biopsy is risky in patients with severe pulmonary arterial hypertension and must be done after careful clinical consideration.
A 13-year-old boy presented with progressive exertional dyspnea for the past 6 months that significantly worsened over the last month; the patient had an episode of syncope on exertion. There was no history of fever, cough, sputum, wheezing, or hemoptysis. Examination revealed mild central cyanosis, tachycardia, and loud P2. There were no murmurs or congestive heart failure. The chest x-ray (Figure 1) showed a dilated main pulmonary artery and bibasilar reticulonodular opacities. There were no Kerley-B lines or pleural effusion. The ECG showed right axis deviation and right ventricular hypertrophy with ST–T changes (Figure 2). The echocardiogram showed a dilated right ventricle with mild tricuspid regurgitation and decreased systolic function. The left ventricular systolic function, mitral valve, and pulmonary veins were normal. The predicted right ventricular systolic pressure was 100 mm Hg. The right atrium was dilated with a stretched foramen ovale with a right to left shunt. A 99mTc microaggregated albumin lung perfusion scintigraphy showed a low probability for pulmonary embolism. Rheumatoid factor, antinuclear antibody tests, and antineutrophil cytoplasmic antibodies were negative. Serum T3, T4, and thyroid-stimulating hormone testing was normal. Rapid screening test for HIV was negative. A computed tomography angiography performed to look for the cause of pulmonary arterial hypertension showed dilated central pulmonary arteries and diffuse, ill-defined centrilobular nodules of ground-glass opacity with basal predominance. However, there was no prominent interlobular septal thickening, pleural effusion, or mediastinal lymphadenopathy. These findings suggested the diagnosis of PCH (Figure 3). A lung biopsy confirmed the diagnosis of PCH (Figures 4A and 4B) The patient succumbed to the illness during the following month.
The cause of PCH remains unknown. The triggers for exuberant capillary growth in the lungs are not clear. It may be associated with secondary PVOD, and the distinction of PCH/PVOD may be difficult.1 The proliferating endothelial cells typically do not show features of malignancy. The natural history of the disease is not well defined. It is a very rare disease, and the prognosis is generally poor. More recently, evidence of increased expression of vascular endothelial growth factor and platelet-derived growth factor activity in patient with PCH has been reported.2 Anecdotal response to interferon-α and angiogenesis inhibitors such as doxycycline have been reported.3,4 Lung transplantation is the only curative therapeutic option available. Better understanding of this entity is warranted.