Abstract

The numbers of mast cells/mm2 of lung parenchyma were counted in four controls, 15 cases of primary plexogenic pulmonary arteriopathy (PPA), and 17 cases in which the arteriopathy was secondary to congenital heart disease, to determine if increased numbers occur in PPA and with what stage of disease they might be associated. Considerable accumulations of lung mast cells may occur in this disease, but these are not closely related to any particular histological stage in the development of the arteriopathy. It is postulated that while mast cells could conceivably exert a vasodilatory effect on constricted small pulmonary arteries, it seems more likely that they are part of the parenchymal changes that commonly develop in this disease.