Queries regarding the blast count
showed interesting results.
There are anecdotal reports that some physicians are handicapping themselves by not following the guidelines to do a 500-cell blast count
In a proportion of patients, hypoplastic MDS and MDS with a low blast count
or a normal karyotype are difficult to distinguish from AA.
A study investigated 805 AML patients aged 20 93 years and found that the NPM1 mutations are associated with high WBC and blast count
in 80 89% of AML patients.
This analysis showed that neither sex and age nor WBC count, absolute blast count
, hemoglobin level, platelet count, prothrombin time, and partial thromboplastin time were significantly related to prognosis in the study population.
In this case, given the low blast counts
and absence of granulocytosis or basophilia, the possibility of CML was unlikely and this FISH study was not performed.
Although fewer patients in Cohort 4 qualified for extended treatment, it is interesting to note that the two who did not qualify for extended treatment were both AML patients with more than 90 percent blast count
10,11) In such cases, the patient should be diagnosed with AML if the distinct cytogenetic abnormalities described above are present, even if the blast count
is less than 20%.
An overall response rate (ORR) as determined by CR, CRi, partial remission, and bone marrow blast count
normalization without blood count recovery was reported by investigators in 20 of 56 subjects for an ORR of 36 percent, with 12 of 56 subjects (21 percent) experiencing a CR or CRi.
In addition, CMML bone marrow samples show dysplasia of the erythrocytic, megakaryocytic, and granulocytic lines; a blast count
of less than 5% but occasionally as high as 20%; and an increase in monocytic precursors.
During transformation to acute leukemia, the blast count
increases to 20-30%.
1 This percentage does not represent a specific biological event in the continuum of an increasing blast count
, but is merely, to the best to our knowledge, a cut-off point that facilitates relatively clear classification and therapeutic planning.
In rare cases, the blast count
is below 20%, but cytogenetic abnormalities are present that by convention warrant a diagnosis of AML (see cytogenetics section below).
Results of Bone Marrow Studies Initial Admission 3 Weeks Later With Varicella With ALL Cellularity Decreased 100% increased Morphology Decreased in all cell lines Total replacement by ALL-L, blasts Blast count
0% 82% Megakaryocytes Decreased Absent ALL = Acute lumphocytic leukemia.
There is a subset of cases of AEL, erythroleukemia subtype, in which the overall blast count
can be low.