Ultrastructure of elastosis in scirrhous carcinoma of the breast.

The stroma of scirrhous breast carcinoma frequently contains an abundance of material with the histologic staining properties of elastic tissue referred to as elastosis. In the present study, this lesion was found to correspond at the ultrastructural level to elastic fibers of various sizes and random orientation. These fibers displayed the two characteristic components, consisting of an amorphous core with a peripheral mantle of microfibrils. Interspersed among the elastic fibers were modified fibroblasts. These cells exhibited an irregular contour with numerous cytoplasmic processes and indentations. Their cytoplasm contained abundant rough endoplasmic reticulum, prominent Golgi complexes, and bundles of filaments. In the extracellular space, elastic fibers were often closely apposed to the plasma membrane of the fibroblasts. Carcinoma cells were also observed in the elastic tissue. It is postulated that fibroblasts, probably under an inductive influence from cancer cells, are the cells responsible for elastic production.