Histopathologic findings of lung vessels in five children with primary pulmonary hypertension.

A histopathologic study was carried out on pulmonary vessels of lung tissues from 5 children with primary pulmonary hypertension (PPH), in whom diagnosis was made on the basis of cardiac catheterization. Histological sections of lung were obtained in 4 patients by open lung biopsy and in one patient by closed needle necropsy soon after death. In all cases the vascular diseases were classified as grade 6 of the Heath-Edwards. Morphologic studies of small pulmonary arteries revealed medial hypertrophy (41.0%), intimal cellular proliferation (2.5%), intimal fibroelastic proliferation (36.9%) and medial destructive changes (19.6%) such as dilatation lesions, plexiform lesions, arteritis, or fibrinoid necrosis. Index of pulmonary vascular disease (IPVD) was 1.6 to 3.4 (mean 2.5). The advancement of these pulmonary changes sufficiently explains the extremely poor prognosis of children with PPH.