Cases occurring in children aged ≤18 years, which represent ~20% of all cases, could be regarded in the non-DS-AMKL category. Cases of the disease not associated with mediastinal germ cell tumors occur in adults who as a group have older median age centering around those 50–70 years old. The disorder is far more fulminant than non-DS-AMKL and DS-AMKL and generally presents with more serious hematological symptoms (e.g. anemia-related) and a much higher incidence of extramedullary manifestations (e.g. organ enlargement, leukemia cutis) than seen in the other two forms of AMKL. Diagnosis
Adult-AMKL commonly occurs in adults in their sixties and seventies but may be seen in adolescents as young as 13. Its diagnosis can be suspected in cases that have either a prior history of MPN or a history or current findings indicating the presence of mediastinal blast cell tumor. In all cases, the diagnosis adult-AMKL rests upon the same determinations used to diagnose DS-AMKL, e.g. increased blast cells in blood and/or bone marrow, immunochemical evidence that these blast cells bear platelet line-specific markers, and occurrence of the genetic aberrations in these blast cells that have been associated with the disease. Treatment
Adult-AMKL has remained poorly responsive to the treatment regiments used in DS-AMKL and non-DS-AMKL. These treatments have given complete remission rates of 43-50%. Prognosis
The prognosis of adult-AMKL in patients treated for the disease is far below that of other forms of AMKL. Their median overall survival times are only 18 to 41 weeks with 5 year survival rates of only 10-11 percent.
Further studies may indicate that this recent cancer chemotherapy regimen plus allogenic bone marrow transplantation in cases which relapse after the first remission are the preferred treatment for non-DS-AMKL. Prognosis
In a review of 153 patients treated for non-DS-AMKL between 1990 and 2014 with various intensive chemotherapy protocols that included cytarabine, an anthracycline (e.g. daunorubicin, doxorubicin), and in 25% of cases human stem cell transplantation, the probability of overall 4 year survival rate, probability of 4 year event-free survival, and probability of 4 year cumulative relapse rate were 56, 51, and 29%, respectively. Patients with non-DS-AMKL given the treatment regimen described for DS-AMKL above had a much better prognosis than patients treated with earlier-devised treatment regimens: their overall survival rate using these regimen was estimated to be 76%. Adult-AMKL
Pathophysiology
Adult-AMKL can result from the progression of other myeloproliferative neoplasms (MPN) viz., chronic myelogenous leukemia, polycythemia vera, essential thrombocytosis, and primary myelofibrosis. In one review of adult-AMKL, 25% of 49 cases were considered as secondary to one of these MPN. The mechanism behind these cases of secondary AMKL are unknown although an inversion in chromosome 3 at positions q21 and q26, i.e. inv(3)(q21q26), is often seen in these secondary cases of adult-AMKL.Rare cases of adult-AMKL also have mediastinal germ cell tumors. These tumors are malignancies of germ cells, i.e. primitive cells that give rise to sperm and ovum cells. In adult-AMKL, mediastinal germ cell tumors that are associated with adult-AMKL are not seminomas (i.e.