Amegakaryocytic thrombocytopenia is either congenital or acquired (amegakaryocytic thrombocytopenic purpura).
Autoimmune diseases, drugs, toxins, hepatic cirrhosis, lymphoproliferative disorders and other malignacies.
Bone marrow is normocellular, erythropoiesis and myelopoiesis are normal. Megakaryocytes are substantially decreased in number or sometimes even completely missing.