Polycythemia associated with primary systemic amyloidosis: elevated levels of hemopoietic factors and cytokines.

A 60-year-old man was diagnosed to have primary systemic amyloidosis (AL type) and polycythemia (Hgb 19.1 g/dl, WBC 14,600/microliters, and platelets 60.5 x 10(4)/microliters). In vitro colony assay for hemopoietic stem cells showed increased numbers of colony-forming units (CFU)-G, CFU-GM, CFU-E, and CFU-Meg. Serum levels of erythropoietin (Epo), granulocyte colony-stimulating factor (G-CSF), interleukin (IL)-3 and IL-6 were elevated. The infiltration of amyloid fibrils into the hemopoietic factor-producing tissues may stimulate abnormal secretion of hemopoietic factors and cytokines, resulting in increased numbers of hemopoietic stem cells and polycythemia in the peripheral blood.