Pulmonary capillary haemangiomatosis-like lesions in severely congested lungs

To elucidate the nature of capillary alterations in the severe form of pulmonary venous congestion (SPVC).

Post-mortem lungs from 52 patients with left-sided cardiac failure were examined, including 31 cases of valvular heart disease and 21 cases of cardiomyopathy. Six post-mortem lungs (six of 52, 11.5%) had patchy lesions composed of markedly widened alveolar walls containing numerous dilated capillaries. These features strikingly mimicked pulmonary capillary haemangiomatosis (PCH). Moreover, one (one of 52, 1.9%) lung showed numerous fibrous micronodules containing capillaries with or without ossification, associated with prominent capillary sprouts, suggesting capillary varicose changes. No pathological features suggesting plexiform angiopathy or veno-occlusive disease were found. Ultrastructural examination revealed occasional interposition of swollen endothelial cells in the thickened basement membranes of the pulmonary capillaries.

PCH-like lesions can occur infrequently as an incidental finding in SPVC, rarely accompanying ossifying fibrocapillary micronodules. These lesions are considered to be a secondary form of PCH, representing severely tortuous and proliferative capillary changes rather than neoplasia.