DIFFERENT DISTRIBUTION OF PLEXIFORM LESIONS IN PRIMARY AND SECONDARY PULMONARY-HYPERTENSION

Despite much interest in plexiform lesions, no published work compares their distribution in different types of pulmonary hypertension. Scat tered reports of plexiform lesions in bronchial arteries oppose the co nsensus view that the lesions develop in pulmonary arteries. To compar e the localization of plexiform lesions in different types of pulmonar y hypertension, and to assess the role of the bronchial arteries in th eir formation, we examined by light microscopy lung tissue from five p atients with primary plexogenic pulmonary arteriopathy (PPPA), six wit h pulmonary hypertension secondary to congenital cardiac malformations (CCM), and one with pulmonary hypertension complicating hepatic cirrh osis. We classified the 270 plexiform lesions observed as either preac inar or intra-acinar based on the type of pulmonary artery in which th ey were located, apd computed the frequencies of each type of lesion w ithin each etiologic group. We searched for lesions developing in bron chial arteries. Then, postulating that a close anatomic relationship b etween plexiform lesions and bronchial arteries would necessitate a cl ustering of the lesions near sites in the lung subserved by the bronch ial circulation, we measured, for 211 of the 270 lesions previously cl assified, the distance from the lesion to the nearest airway and compu ted the mean lesion-to-airway distance in each etiologic group. The fr equencies of preacinar plexiform lesions were 34% in PPPA, 67% in CCM (P < .01), and 21% in the case of cirrhosis. We found no plexiform les ions within bronchial arteries, and the mean plexiform lesion-to-airwa y distances were 1,680 +/- 180 mu m in PPPA, 1,330 +/- 220 Crm in CCM, and 2,050 +/- 1,090 mu m in cirrhosis (P > .05). Our data suggest tha t (1) the distribution of plexiform lesions within the pulmonary arter ial tree varies depending on the etiology, (2) plexiform lesions rarel y if ever arise in bronchial arteries, and (3) plexiform lesions are n ot preferentially distributed near parts of the lung subserved by the bronchial circulation. Copyright (C) 1995 by W.B. Saunders Company