Laboratory diagnosis of acute leukemia in Iraq, the available options

Abstract

Diagnosis of acute leukemia in Iraq is mainly dependent on the personal experience of the laboratory physician. Local guidelines in this field were never proposed and the international guidelines are very difficult to apply as the only available techniques include morphology of peripheral blood and bone marrow specimens plus very limited immunohistochemistry CD markers and PCR testing for BCR-ABL oncogene only, therefore the aim for diagnosis, classification and subclassification of acute leukemia in this country should be that of diagnosis and lineage assignment that serves a clear therapeutic goal.Having been working in the field of laboratory hematology since 2003 in the major teaching hospitals in Baghdad, I found that the following scheme is the available useful option:Acute leukemia should be classified on the basis of FAB group, but using a cut-off point of 20% blast cells, as proposed in the WHO classification [1]. Acute myeloid leukemiaWith Romanowsky stain morphology AML-M2, M3, M4, M5b and M6 can be recognized readily.By adding few special stains such as Sudan black B (SBB) [2] (and not myeloperoxidase as SBB has a little more sensitivity in detecting myeloblasts which is the crucial point), plus a non-specific esterase stain as -naphthyl acetate esterase it becomes possible to recognize AML-M1 and most cases of AML-M5a [3].The AML cases that cannot be distinguished by morphology and cytochemistry, specifically M0 and M7, for which the presence of myeloid dysplasia in the former and the cytoplasmic blebs in the latter may give a hint for the probable diagnosis, however there is still the need for more positive diagnostic technique and as the flow cytometry immunophenotyping is not available then the use of a limited number of CD markers study by immunohistochemistry to identify the lineage of acute leukaemia is the option, these include CD33, anti-myeloperoxidase and CD41.Rare types of AML like M5c require high degree of morphology experience, in which malignant cells appearance is reminiscent of tissue histiocytes [4].There is still a small proportion of cases that would be only certainly diagnosed after the response to treatment as in rare forms of AML-M3v [5].

Pattern of hematological malignancies diagnosed by peripheral smear examination

“…5 Therefore, where these expensive machines are not available, the laboratory diagnosis would mostly depend on more basic laboratory techniques that should at least include complete blood count (CBC) and peripheral blood morphology, followed by cytochemistry. 5,6 For the diagnosis of AML/ALL, FAB classification of acute leukemia should be applied in under-resourced laboratories where the only available routine techniques for diagnosis are morphology and cytochemical stains. 5,6 In the WHO classification of acute leukemia, the diagnosis is based on an arbitrary cut-off point of 20% blasts as a percentage of bone marrow total or nonerythroid cells or as a percentage of peripheral blood cells.…”

“…5,6 For the diagnosis of AML/ALL, FAB classification of acute leukemia should be applied in under-resourced laboratories where the only available routine techniques for diagnosis are morphology and cytochemical stains. 5,6 In the WHO classification of acute leukemia, the diagnosis is based on an arbitrary cut-off point of 20% blasts as a percentage of bone marrow total or nonerythroid cells or as a percentage of peripheral blood cells. 7 This exact percent is also applied nowadays in underresourced laboratories where the FAB classification is used.…”

“…4 The diagnosis involves a multiparameter approach including morphologic examination and phenotypic or genotypic studies. 5 However; the smear offers a window into the functional status of the bone marrow, the factory producing all blood elements. Review of the smear is an important adjunct to other clinical data.…”

Diagnosis of Acute Leukemia in Under-Resourced Laboratories

“…FAB classification (Table 2) of acute leukemia should be applied in under-resourced laboratories where the only available routine techniques for diagnosis are morphology and special stains (Abdulsalam, 2010). The scheme in (Figure 1) may be used as a general guideline for the diagnosis of acute leukemia in under-resourced laboratories; however, it should be modified to optimally fit into the locally available techniques.…”

“…Sketching rational systematic schemes for optimum use of the locally available investigation options would usually permit the diagnosis of most varieties of acute leukemias with a very acceptable level of reliability. Also these schemes may provide invaluable information regarding the prospect of update and future plans for laboratory development as it can show clearly where the weak joints are (Abdulsalam, 2010).…”