Acute erythrocyte leukemia is a rare form of acute myeloid leukemia (less than 5% of AML cases) where the myeloproliferation is of erythrocytic precursors. It is defined as type "M6" under the FAB classification. Signs and symptoms The most common symptoms of AEL are related to pancytopenia (a shortage of all types of blood cells), including fatigue, infections, and mucocutaneous bleeding. Almost half of people with AEL exhibit weight loss, fever and night sweats at the time of diagnosis. Almost all people with AEL are anemic, and 77% have a hemoglobin level under 10.0 g/dl. Signs of thrombocytopenia are found in about half of people with AEL. Causes The causes of AEL are unknown. Prior to a 2008 reclassification by the World Health Organization, cases that evolved from myelodysplastic syndromes, myeloproliferative neoplasms, chemotherapy for other cancers or exposure to toxins were defined as secondary AEL. These cases are now likely to instead be classified as acute myeloid leukemia with myelodysplasia-related changes or therapy-related AML. + Diagnosis Acute erythroid leukemias can be classified as follows: M6a (Erythroleukemia) 50% or more of all nucleated bone marrow cells are erythroblasts, dyserythropoiesis is prominent and 20% or more of the remaining cells (non- erythroid) are myeloblasts. M6b (Pure erythroid leukemia) In rare cases the erythroid lineage is the only obvious component of an acute leukemia; a myeloblast component is not apparent. The erythroid component consists predominantly or exclusively of proerythroblasts and early basophilic erythroblasts. These cells may constitute 90% or more of the marrow elements. Despite this lack of myeloblasts, these cases should be considered acute leukemias. In a WHO proposal the blastic leukemias that are limited to the erythroid series are designated pure erythroid malignancies. M6c (Erythroleukemia and Pure erythroid leukemia) Myeloblast- and proerythroblast-rich mixed variant. Treatment Treatment for erythroleukemia generally follows that for other types of AML, not otherwise specified. It consists of chemotherapy, frequently consisting of cytarabine, daunorubicin, and idarubicin. It can also involve bone marrow transplantation. Prognosis Information on prognosis is limited by the rarity of the condition. Prognosis appears to be no different from AML in general, taking into account other risk factors. Acute erythroid leukemia (M6) has a relatively poor prognosis. A 2010 study of 124 patients found a median overall survival of 8 months. A 2009 study on 91 patients found a median overall survival for erythroleukemia patients of 36 weeks, with no statistically significant difference to