Large aggregates of insoluble, denatured ferritin from which iron is less readily available. Hemosiderin is found only within cells (it is not present in blood). Hemosiderin increases in pathological iron overload states. When present in sufficient amounts, both ferritin (which is soluble) and hemosiderin (insoluble) can be recognized grossly or in the light microscope by their rusty or yellow-brown color. Both are detected microscopically using Prussian (Berlin) blue stain for trivalent iron.
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