Alveolar capillary basement membrane lesions in Goodpasture's syndrome and idiopathic pulmonary hemosiderosis.

An ultrastructural study of lung distinguised between lesions of the alveolar capillary basement membrane in a case of Good pasture's syndrome and in three cases of idiopathic pulmonary hemosiderosis. In Goodpasture's syndrome, diffuse vascular injury with wide endothelial gaps, diffusely fragmented basement membranes and an electron dense layer on the basement membrane was found. In idiopathic pulmonary hemosiderosis, focal ruptures of the basement membrane were associated with hydropic changes in pneumocytes and, although fibroblasts were not seen, collagen deposition occurred within the basement membrane. immunofluorescent studies failed to show deposition of immunoglobulins G (IgG), A (IgA), M (IgM) or C3 in the lung in either disease. The ultrastructural lesions appear to separate these clinically similar entities.