Acute promyelocytic leukemia M3: cytomorphologic, immunophenotypic, cytogenetic, and molecular variants

Phenotypic clues that predict underlying cytogenetic/genetic abnormalities in myeloid malignancies: A contemporary review

Precise subclassification of myeloid malignancies per the World Health Organization (WHO) classification system and the International Consensus Classification of Myeloid Neoplasms and Acute Leukaemias (ICC) requires investigation and documentation of the presence of cytogenetic and/or molecular genetic changes. These ancillary studies not only help in diagnosis, but also the prognosis of disease; however, they take time to be completed. In contrast, morphological evaluation of material from the blood and bone marrow specimens of cases where myeloid malignancies are suspected is usually completed quickly. Cytomorphological assessment may predict genetic changes and can be helpful in triaging acuity. This is especially true in haematological emergencies such as acute promyelocytic leukaemia (APL), where prompt APL-specific therapy can be life changing. Similarly, some morphological clues may help identify core binding factor leukaemias where a diagnosis of acute myeloid leukaemia (AML) could be rendered without reaching the 20% blast cutoff with immediate treatment-decision implications, or even a subset of cases of AML with FLT3 ITD/NPM1 mutation(s) which show characteristic features. Even though FISH/cytogenetics and/or PCR are still required for establishing the final diagnosis, evaluation for the presence of specific cytomorphological features that help predict genetic changes can be a useful tool to help guide early therapy.

The Survival of Patients with t(15;17)(q22;q12) Positive Acute Promyelocytic Leukemia: A Study in North-East of Iran

Background & Objective

Acute promyelocytic leukemia (APL) with t(15;17)(q22;q12) is a relatively common subtype of acute myeloid leukemia (AML). Here, our objective was to ascertain the survival of patients with this leukemia in north-east of Iran.

Methods

Survival rates of 42 APL patients with t(15;17)(q22;q12) were assessed. Clinical information was obtained from archived medical records. Statistical analysis was performed by SPSS 18 software using log-ranked test and Kaplan Maier survival analysis.

Results

Females and males comprised 49% and 51%, respectively. The mean age at diagnosis was 34.3 ± 14.1 years old. During the study period, 17 demises occurred in males, while this number was 7 in females. The mean survival of patients (month) was 23.22 ± 3.57 (95% CI: 16.21 ± 30.2). The five-year survival rate obtained 30%. Regarding demographic and clinical features, the highest rates of 5-year survival were recorded in patients with 20-35 years old (47.6%), males (51%), white blood cell count <10 × 10 9 /l (48%), and platelet count >140 × 10 9 /l (100%).

Conclusion

Younger age, lower WBC count and higher platelet count were significantly associated with longer survival in AML patients with t(15;17)(q22; q12).

Recurrent Arterial Thrombosis as a Presenting Feature of a Variant M3-Acute Promyelocytic Leukemia

Acute limb ischemia (ALI) is a common vascular emergency. Hematologic malignancies are commonly associated with derangement of normal hemostasis and thrombo-hemorrhagic symptoms during the course of the disease are common. However, ALI as an initial presenting feature of acute leukemia is rare. Due to the rarity of this presentation, there is a scarcity of prospective randomized data to optimally guide the management of these patients. Current knowledge is mainly based on isolated cases. We report our experience managing a patient who presented with ALI and was found to have occult leukemia. A review of all cases with ALI as a presenting feature of acute leukemia is also presented.

Rapid detection of t(15;17)(q24;q21) in acute promyelocytic leukaemia by microwave-assisted fluorescence in situ hybridization

Acute promyelocytic leukaemia (APL) is a hematologic malignancy characterized by the rearrangement of the PML and RARα genes, mostly due to a reciprocal chromosomal translocation t(15;17)(q24;q21). A quick APL diagnosis is essential for starting a prompt suitable therapy. We describe a new rapid diagnostic laboratory approach to detect the PML-RARα rearrangement, which gives clear genetic results within 30 min of hybridization. It combines quick cell harvesting, fluorescence in situ hybridization performed with commercial DNA probe and microwave beams supplied by a domestic microwave oven. Copyright © 2015 John Wiley & Sons, Ltd.

Comparative study of the efficacy of Wright-Giemsa stain and Liu's stain in the detection of Auer rods in acute promyelocytic leukemia

In view of the importance of Auer rods in the rapid diagnosis of acute promyelocytic leukemia, we compared the results of Wright-Giemsa stain and Liu's stain (a rapid and simple stain, which is also a kind of modified Romanowsky stain) in the detection of Auer rods. This study was based on 53 cases of acute promyelocytic leukemia. Two staining methods were respectively performed on the bone marrow smears of these cases, and presence of Auer rods as well as nuclear features, cytoplasmic features and the degree of granularity of the cytoplasm were compared in each case. Our results showed that the occurrence of Auer rods as well as faggots in leukemic promyelocytes were significantly higher under Liu's stain than under Wright-Giemsa stain. Significant differences also existed in the occurrence of hypergranular cells and cytoplasmic protrusions between smears stained with Liu's stain and Wright-Giemsa stain. Liu's stain is important for the rapid diagnosis of suspicious APL, especially in recognizing Auer rods.

Acute promyelocytic leukemia, hypogranular variant: a rare presentation

Early diagnosis of acute promyelocytic leukemia (APL) is essential because of its associated life threatening coagulopathy and unique response to all trans-retinoic acid (ATRA) therapy. The characteristic cell morphology supplemented by cytochemistry offers the most rapid means for diagnosis. Here we describe a rare case of acute promyelocytic leukemia-hypogranular variant that poses particular diagnostic challenge.

Identification of PML–RARA rearrangement by RT-PCR and sequencing in an acute promyelocytic leukemia without t(15;17) on G-banding and FISH

Acute promyelocytic leukemia (APL) is characterized by a reciprocal translocation, t(15;17) (q22;q12), resulting in fusion of the genes promyelocytic leukemia (PML) and retinoic acid receptor alpha (RARA). With conventional cytogenetic methods, these translocations are detected in about 70-90% of patients, with most of the negative results due to technical problems or cryptic variants. Those masked PML-RARA fusions can be identified by molecular analyses such as reverse transcriptase-polymerase chain reaction (PCR) and fluorescence in situ hybridization (FISH). We have studied a patient showing morphological, cytochemical, and immunophenotypic features of hypergranular APL with trisomy 8 as a sole anomaly. t(15;17) was not evident on FISH tests, while RT-PCR and cDNA sequencing revealed the presence of PML-RARA transcripts.

Late relapses in acute promyelocytic leukaemia

From January 1988 to December 1997, among 53 acute promyelocytic leukaemia patients in 1st complete remission (CR) after 5 years from diagnosis, we observed 5 late relapses (9.4%) after 60, 61, 71, 101 and 155 months from diagnosis; 3 of those late relapses (7.7%) occurred among 39 patients previously treated with all-trans-retinoic acid. An involvement of the mastoid occurred in 3/5 patients (60%), compared with 2/32 patients (6.3%) at an early relapse (p < 0.02). As to the treatment of the late relapse, 1 patient received all-trans-retinoic acid alone followed by allogeneic transplantation and 4 patients were treated according to the GIMEMA 0191 protocol. All patients achieved a 2nd CR and are still alive: 4 in the 2nd molecular CR after 6, 33, 34 and 115 months; 1 relapsed after 15 months and is now in the 3rd CR. In conclusion, a late relapse occurred in a sizeable fraction of acute promyelocytic leukaemia patients: the high rate of ear involvement might be explained considering the ear as a 'disease sanctuary'.

PML-RARalpha fusion gene transcripts and biological features in acute promyelocytic leukemia patients

Acute promyelocytic leukemia (APL) is characterized by the presence of rearrangements involving the retinoic acid receptor alpha (RARalpha) gene and a variable incidence in different populations. The hybrid gene PML-RARalpha, present in 98% of cases, encodes a fusion protein essential to the pathogenesis of the disease. Depending of the PML's gene breakpoint in chromosome 15, the transcript subtypes bcr1, bcr2 and bcr3 may be formed. The correlation between these transcript subtypes and clinical parameters is still controversial. The objective of this study was to determine the frequencies of the PML-RARalpha transcripts and subtypes in a series of 32 APL patients from Northeast Brazil and to evaluate the association of these subtypes to different parameters. The method used was RT-PCR. The frequency of our APL cases is approximately 28% of the acute leukemias. The results showed the presence of PML-RARalpha isoform in all patients and a higher frequency of the bcr1/2 subtype. No significant statistical association was found between molecular subtypes and age, sex, French-American-British (FAB) classification, leukocyte and platelet count, hemoglobin level or coagulation tests. In conclusion, these data suggest similar molecular and biological features for our APL patients at diagnosis in comparison with those reported in current scientific literature.

Deletion of MYC and presence of double minutes with MYC amplification in a morphologic acute promyelocytic leukemia–like case lacking RARA rearrangement: could early exclusion of double-minute chromosomes be a prognostic factor?

Gene amplification on double minutes is rarely found in acute myeloid leukemia (AML) and is often linked to poor prognosis. It is often associated with acute myeloid leukemia with differentiation (AML-M2) and is rarely reported in acute promyelocytic leukemia (APL), which is characterized in the vast majority of cases by the reciprocal t(15;17)(q22;q21) with resultant translation of an abnormal PML-RARA fusion protein. Most of the rare cases of APL that lack this translocation have a demonstrable RARA breakpoint. We report on a morphologic APL-like case lacking t(15;17) and the RARA breakpoint and also has the deletion MYC of 8q24 associated with the occurrence of MYC amplification on double-minute chromosomes (dmin). Excessive exclusion of dmin was observed at the initial diagnosis. These findings are compared to the few cases previously reported in the literature.

Pro-proliferative function of the long isoform of PML-RARalpha involved in acute promyelocytic leukemia

The promyelocytic leukemia (PML) gene codes for a tumor suppressor protein that is associated with distinct subnuclear macromolecular structures called the PML bodies. The PML gene is frequently involved in the t(15;17) chromosomal translocation of acute promyelocytic leukemia (APL). The translocation results in a fusion gene product, PML-RARalpha, in which the PML gene fuses to the retinoic acid receptor alpha (RARalpha) gene. PML-RARalpha has been shown to promote transcriptional repression of genes involved in myeloid terminal differentiation and to disrupt the architecture of PML bodies, a phenotype reversed by treatment with all trans retinoic acid (ATRA). However, there are several alternatively spliced isoforms of PML-RARalpha. Here, we addressed the differences between the short and the long isoforms of PML-RARalpha (L and S) since both are associated with APL. We demonstrate that PML-RARalphaL, but not PML-RARalphaS, can directly promote cell growth by transcriptionally activating the pro-proliferative gene, c-fos, in response to mitogenic stimulation. The activity of the PML-RARalphaL is completely sensitive to ATRA. We further show that this activation is not via direct recruitment of the protein to the c-fos promoter but indirectly by altering the chromosomal environment of the c-fos gene, thereby rendering it more accessible to the signal induced transcriptional activators. Our results suggest that in addition to antagonizing the PML-tumor suppressor or the PML-pro-apoptotic activity, PML-RARalpha proteins can also directly promote cell growth by activating c-fos.