<unk>  is a rare type of hematological malignancy that results from the clonal proliferation of megakaryoblasts in the bone marrow. Prof. Dr. Von Boros first described it in 1931. In 1985, the French-British-American classification of Acute myeloid leukemia (AML) included it as <unk>  subtype). Later in 2008,<unk>  was classified under AML otherwise not specified category by World Health Organization. It results from a mutation involving several genes, particularly the GATA1 gene, and transforming growth factor-β (TG-β).<unk>  has commonly associated with Down syndrome. It has a bimodal distribution and is more common in children (<4) 15% than adults 0.6%.<unk>  has a wide range of presentations which has either acute or insidious onset. It is characterized by fever, irritability, headache, fatigue, bone pain, generalized body aches, bruises, and difficulty walking. Physical exam findings include pallor, Hepatosplenomegaly (HSM), and lymphadenopathy, bruises and purpura, and sometimes temporal or orbital swelling. It is diagnosed by bone marrow biopsy showing 30% or more leukemic cells of megakaryocytic lineage and detection of platelet-specific peroxidase antibodies. Other lab findings include pancytopenia and megakaryocytic progenitors in the peripheral smear. Other diagnostic studies include; Immunophenotyping using MoAb to megakaryocyte restricted antigen (CD41 and CD61), complex karyotypic (t(1;22)(p13;q13) involvement, radiologic features of the osteolytic lesion, metaphyseal lucency, pathologic fractures using CXR, CT scan, bone scan, and MRI modalities. Currently, chemotherapy and allogeneic bone marrow transplant (Allo-BMT) are mainstay therapy. However, treatment-related toxicity is a big challenge. Different drug combination regimens are available for<unk> . The commonly used drugs are Cytarabine, mitoxantrone, etoposide, vincristine, fludarabine, and pirarubicin. The prognosis of<unk>  in Down syndrome patients is favorable as compared with non-Down syndrome patients.
The following complications can be observed in patients with<unk> ; periosteal elevation, osteolytic lesions, especially in long bones, e.g., femur, osteoporosis with pathologic fractures, Sweet syndrome (SS), leukemia cutis, and hypercalcemia.
Acute megakaryoblastic leukemia
Prolymphocytic leukemia
Myeloid leukemia
Acute myeloblastic leukemia
Acute myelomonocytic leukemia
Acute promyelocytic leukemia
Monocytic leukemia
Juvenile myelomonocytic leukemia