Monosomy 7 in patients with aplastic anemia and paroxysmal nocturnal hemoglobinuria with evolution into acute myeloid leukemia.

We report two cases of Thai patients with aplastic anemia/paroxysmal nocturnal hemoglobinuria (AA/PNH) who subsequently developed acute myeloid leukemia (AML) at their terminal phase. Monosomy 7 was demonstrated upon karyotypic analysis of bone marrow in both cases at the time leukemia developed The first patient was a 25-year-old man diagnosed with AA at age 14, recovered from AA at age 15, developed PNH at age 21 and turned into AML at age 25. The second patient was a 27-year-old man diagnosed with PNH at age 22, developed severe AA at age 25 and turned into AML at age 27. This latter patient received anti-lymphocyte globulin when he developed severe AA but did not respond well whereas the first patient fully recovered from AA with anabolic hormone treatment. Time to diagnosis of AML in the patient who received immunosuppressive therapy was strikingly shorter than that who received conventional androgen therapy (2 years vs 11 years after AA, respectively). The presence of monosomy 7 in leukemic cells of both patients emphasizes its central role in the development of AML from AA/PNH. However, other factors such as choice of AA/PNH therapy and patients response may modulate the time to emergence of monosomy 7-carrying AML clone and frank leukemia. Further studies into the biologic and genetic mechanisms involved in the development of leukemic clone arising from AA/PNH should be explored.

Immunophenotypic profile of adult acute myeloid leukemia (AML): analysis of 267 cases in Thailand.

Little data exists in Thailand and other Southeast Asian countries regarding the biological characteristics of adult acute myeloid leukemia (AML). In this study, we performed a flow cytometric analysis of 267 Thai adult AML cases to delineate the pattern of leukemic cell surface antigens. Forty-eight cases (18%) were identified as acute promyelocytic leukemia (M3) and 219 cases as non-M3. The most frequent subtype of AML in Thailand was M1/M2 and the least frequent was M7. M3 immunophenotypes were characterized by their unique lack of expression of CD34 and HLA-DR as contrast to the high mean expression of 50% and 70%, respectively, in non-M3. Overall, 60% of cases expressed CD34. Aberrant lymphoid antigens were uniquely seen in specific subtypes of Thai AML, including CD19 (33% of non-M3 vs 23% of M3) and CD2 (12% of M3 vs 2% of non-M3). CD56 was frequently expressed in both M3 and non-M3 while CD16 appeared to be associated with M4/M5 (24% of cases) and CD7 with M1/M2 (21% of cases). Eighty-one percent of non-M3 expressed CD38 while only 53% of M3 did. We found that most Thai adult AML patients were on average 15-20 years younger than those of the West or Japan with only 25% of Thai cases over 60 years of age, although the immunophenotypes were not markedly different. Biological studies of acute leukemia in various countries should help to provide epidemiological clues that play a role in the pathogenesis of leukemia in different geographic regions of the world. Our study represents the largest series of AML ever investigated in the Southeast Asian region.