Pulmonary alveolar septal amyloidosis. A scanning- and transmission electron microscopy study

A case of primary amyloidosis is presented with diffusely involved the alveolar septa. The lung was studied by light microscopy and by transmission and scanning electron microscopy. The fine structure of the amyloid material showed it to be porous, homogeneous, and an acellular substance consisting of interwoven bundles of amyloid fibrils. The fine structure of the amyloid material was considered to explain the normal gas diffusion across the alveolar respiratory membrane. The diagnosis of amyloidosis was first made from a uterine cervical biopsy specimen.