On the Origin of Amyloid

Abstract

A case of multiple myeloma presented with multiple amyloid tumors 1 1/2 yr. before the appearance of other manifestations of disease. Their amyloid nature and the presence of systemic amyloidosis were confirmed in scalp and rectal biopsies by the typical green birefringence of Congo red-stained deposits. Electron microscopic studies of a scalp nodule revealed a practically avascular amyloid mass. The sparse cellular population consisted solely of fibrocytes, fibroblasts and rare histiocytes. The fibroblasts alone showed signs of active secretion and sometimes appeared isolated in a sea of surrounding amyloid. No plasma cells were seen. The amyloid filaments were 50-100A in diameter and showed a periodic 55A beading or cross-striation, composed of 30A dark and 25A bright areas. Abnormal collagen fibrils, with diameters up to 2000A and serrated cross-sectional contour occurred within and outside amyloid deposits. Thick filaments of unidentifiable nature with a 100-200A diameter and suggestion of 100-200A periodicity were seen in relation to pathological collagen fibrils, and also among typical amyloid filaments in areas where collagen was absent. Amyloid is a variant of 1 of the normal scleroproteins, which links amyloid to the reticulin-collagen group and intimates that the fibroblast is responsible for its formation.