Overall bone marrow failure may be congenital (such as Fanconi's syndrome) or aquired after exposition to myelotoxic agents (chemotherapeutics and other drugs, toxins, some (especially viral) infections etc.
The marrow is hypocellular (0 – 30%) with reduced trilinear hematopoiesis. The depression of myelopiesis and megakaryocytes is usually more distinct than erytropoietic depression, therefore erytropoiesis relatively predominates. Lymphocytes, plasma cells, mast cells and macrophages with abundant iron deposits are reactively increased in number.