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Mædica - a Journal of Clinical Medicine
Acute promyelocytic leukemia
microgranular variant –
A clinical and therapeutical approach
Diana CISLEANU, MDa*; Ana-Maria VLADAREANU, MD, PhDa*; Mihaela DERVESTEANU, MDa; Minodora ONISAI, MDa; Horia BUMBEA, MDa; Sinziana RADESI, MDa; Cristina CIUFU, MDa; Anca NICOLESCU, MDa; aDepartment of Hematology, Emergency Universitary Hospital of Bucharest, Romania bRitus-Biotec Molecular Biology Laboratory, Codlea – Brasov, Romania ABSTRACT
Acute promyelocytic leukemia (APL) is a rare form of acute myeloid leukemia with a particular diagnosis
and therapeutic approach. APL represents only 10-15% of acute myeloid leukemia in adults. The mediandiagnosis age is around 40 years. APL’s main genetic event is the translocation between chromosome 15and chromosome 17 – t(15;17)(q22;q21) – generating the PML-RARα fusion gene. APL has four differentsubtypes: the classic form M3 hypergranular, the microgranular variant, the hyperbasophilic form andzinc-finger form, recently described, which is characterized by the presence of a different translocation,between chromosome 11 and chromosome 17:t(11,17)(q23, q11-12). Clinically, patients associatehemorrhagic manifestations and life threatening coagulopathy. Secondary acute myeloid leukemias constitute an entity with a growing incidence in the last few years due to the leukemogenic effect of radiotherapy and several antineoplastic agents for solid tumors, even ifadministrated at low doses (4). We chose to report the case of a 67 year-old woman diagnosed with APL-variant type, who has a history of breast cancer treated by surgery, chemo- and radiotherapy twenty years before the leukemia was diagnosed. Keywords: acute promyelocytic leukemia, PML/RARα, ATRA, complete molecular
INTRODUCTION
younger than in the other subtypes of AML (70 years). The disease may be the consequence of prior therapy for an unrelated malignancy; in these cases, the prognosis is as good as the one for the individuals who present with de novo disease, in contrast with other subtypes of AML in adults. The median age at the time of AML in which the prognosis is significantly of the diagnosis is around 40 years, which Address for correspondence:Ana-Maria Vladareanu, Chairman, Associated Professor Department of Hematology, Emergency Universitary Hospital, 169 SplaiulIndependentei, Zip Code 050098, Bucharest, Romaniaemail address: [email protected] Mædica A Journal of Clinical Medicine, Volume 2 No.4 2007 ACUTE PROMYELOCYTIC LEUKEMIA MICROGRANULAR VARIANT – A CLINICAL AND THERAPEUTICAL APPROACH APL is due to a translocation between chro- effusions, hypotension, renal dysfunction (9,10).
mosome 15 and chromosome 17, which is the The median time of onset is 7 days after ATRA result of two chromosome breaks. The break in chromosome 15 disrupts the promyelocytic asone has proved efficacy in RAS management.
leukemia (PML) gene which encodes a growth In patients who relapse, treatment may include suppressing transcription factor. The break in arsenic trioxide, monoclonal antibodies, bone chromosome 17 interrupts the retinoic acid marrow transplantation (11,12,13,14,15). ‰ receptor alpha (RARα) gene which regulatesmyeloid differentiation. The translocation cre- FULL CASE STUDY
ates the PML/RARα fusion gene. It produces achimeric protein which arrests the maturation The patient is a 67-year-old woman who is of myeloid cells at the promyelocytic stage.
hypertensive, dyslipidemic, with a history of APL has four different subtypes: the classic breast cancer treated by surgery, chemo- and radiotherapy (1988), myocardial infarction variant, the hyperbasophilic form and the zinc- (2001), with early angina pectoris; she was in finger form, recently described, which has a her usual state of health until 2 weeks prior to different translocation, between chromosome 11 and chromosome 17 – t (11,17)(q23, q11- began to complain of fatigue, gingival bleeding, The characteristic clinical features of APL The physical examination revealed pallor, include hemorrhagic manifestations and life few ecchymotic areas on the upper and lower nopathy or hepatosplenomegaly were noted.
changed with the discovery of the activity of all trans-retinoic acid (ATRA) in this disease (1,5).
(Hb) 7.9g/dl, hematocrit (Ht) 23.2%, platelet APL has become the most curable of all acute myeloid leukemia subtypes, by using the cur-rent therapy, including ATRA and anthracycline- Morphology
based chemotherapy and maintenance therapywith ATRA (6,7,8). ATRA therapy has one serious and specific complication: retinoic acid syndrome (RAS). RAS is characterized by signs granules and Auer rods (Figure 1,2).
and symptoms: fever, dyspnea, leukocytosis, The bone marrow aspirate revealed hyper-
pulmonary infiltrates, pleural or pericardial cellularity, with 88% atypical promyelocyteswith folded nuclei, basophilic cytoplasm and fewwith granules and Auer rods. Immunophenotype: the flow cytometric
examination revealed that the blasts were
CD33+, CD34+, CD65w+, CD117+/-, CD2
low+, CD56-/+ HLA-DR low+ and negative
for CD14, CD15 (Figure 3) (16).
At the time of the diagnosis, it was also collected a peripheral blood sample for molec-
ular detection (Reverse transcriptase poly-
merase chain reaction) of PML/RARα, which
revealed the presence of the molecular genetic
marker of APL (17). It was used the quantitative
RT-PCR method (26).
In this particular case, the laboratory tests were negative for disseminated intravascular FIGURE 1 and FIGURE 2. Review of the peripheral smear
coagulation (normal PT, INR, APTT, fibrinogen confirmed the presence of abnormal promyelocytes, with folded level, D-Dimers), otherwise frequently present nuclei, irregular borders, less prominent granules, few withAuer rods.
Mædica A Journal of Clinical Medicine, Volume 2 No.4 2007 ACUTE PROMYELOCYTIC LEUKEMIA MICROGRANULAR VARIANT – A CLINICAL AND THERAPEUTICAL APPROACH Diagnosis
Based on the available data, the diagnosis of
microgranular variant – was established. Thepositive diagnosis was suggested by the clinicalfeatures (hemorrhagic findings), and thecharacteristic morphologic findings on peripheralblood and bone marrow smears examination.
Flow cytometry (18) and reverse transcriptasepolymerase chain reaction were also performedin order to confirm the diagnosis and to allow adifferential diagnosis from acute monocyticleukemia.
The differential diagnosis (19) of APL
microgranular variant includes the classic formM3 hypergranular.
Differential diagnosis of the microgranular variant also includes other acute non-lymphoidleukemia, monocytic subtypes (AML4, AML5).
variant may sometimes be mistakenly identifiedas being of monocytic origin, based on thefeatures of the blasts, especially the folded nuclei.
The presence of the Auer rods in the micro-granular variant and their absence in mono-blasts, as well as the lack of granules, make thedifference between the two forms.
Cytochemistry (Figure 4): promyelocytic cells
are positive for myeloperoxidase, while mono-cytic blasts show non-specific esterase activity.
Flow cytometry (Figure 3): the presence of
myeloid lineage markers (CD33, CD65w) andthe absence of monocytoid lineage antigens(CD14 and CD64 high positive). In this particularcase we found some aberrant expressions ofmyeloid markers for a promyelocytic acuteleukemia, i.e. CD117 (c-kit), CD34 and lack ofCD15, that suggest an immature phenotype,frequently associated with microgranular variant FIGURE 3. Dot-plot histograms in APL: Atypical
Promyelocytes (colored in violet) with the following profile:
CD33+ CD65w+ CD34+ CD117+/- CD64low+ CD2low+ HLA-
DR low+ CD56-/+ CD14- CD15-. FACS-Calibur acquisition,
FIGURE 4. Peroxidase stain on bone marrow
Mædica A Journal of Clinical Medicine, Volume 2 No.4 2007 ACUTE PROMYELOCYTIC LEUKEMIA MICROGRANULAR VARIANT – A CLINICAL AND THERAPEUTICAL APPROACH (27). The expression of HLA-DR is also low chemotherapy, the patient required the usual positive, not usual for this diagnosis, but it was blood product support and antimicrobials. The reported in some papers. Low positivity expres- high dose dexamethasone treatment induced sion of CD2 suggest microgranular variant, also high levels of glucose that necessitated insulin Prognosis
chieved after induction course and confirmed by bone marrow aspiration. After receiving one t diagnosis we identified features that predict course of induction chemotherapy, the patient a high risk for relapse; the old age, elevated was subjected to consolidation therapy, first cycle WBC at presentation, low platelets count.
with idarubicin (5mg/m2/day for 4 days) and variant, and the onset hyperleukocytosis are mitoxantrone (10mg/m2/day for 5 days) and the associated with higher incidence of RAS and third one with idarubicin (5 mg/m2 for a single DIC, increasing the early mortality and morbid- At the end of the consolidation courses, a follow up study of the molecular response was of associated cardiac pathology that limits the recommended and it confirmed the molecular therapeutic possibilities (anthracyclines used in remission (PML-RARα transcript was negative).
was: ATRA 45mg/m2 for 15 days/quarterly inassociation with Methotrexate 15mg/m2 weekly Treatment
and Mercapthopurine 50mg/m2 daily for one Treatment monitoring
The patient underwent the classic induction therapy with all-trans-retinoic acid and an- predict the relapse risk and permit early thracyclines (6,7,8). APL is the first known therapeutic intervention before overt clinical disease that is clinically sensitive to differentiation relapse occur. RT-PCR for PML/RARα should therapy. ATRA given as a single therapeutic agentis associated with short remissions and relapse; be performed every three months for the first that is why combined chemotherapy (ATRA with 2 years and every six months for the following conventional chemotherapy) is recommended, with prolonged disease-free survival (20, 21, 22,23, 24, 25).
The patient received induction therapy with Conclusion
mitoxantrone (10mg/m2/day, for three days), Acute promyelocytic leukemia (APL) is a biologically and ATRA (45mg/m2/day) and low doses of dexa- clinically distinct type of acute myeloid leukemia. Sometimes methasone for ATRA syndrome prophylaxis.
it can occur after chemotherapy for another cancer, especially after use of topoisomerase II inhibitors. In contrast to other rubicin, because of the lower cardiac toxicity.
AML types this is not a predictor of poor prognosis in APL.
On the third day of the treatment, the patient The patient presented is a 67 years woman with secondary acute promyelocytic leukemia microgranular variant that is distress, radiographic pulmonary infiltrates, and probably related to treatment for breast cancer. Immuno- episodic hypertension, without renal failure.
phenotyic profile was atypical for APL, with immature markers RAS was blocked by treatment with high doses and correlate to microgranular variant. She experienced a of dexamethasone (10 mg iv every 12 hours), good outcome with persistent complete molecular remission, oxygen, diuretics (9,10). Favorable evolution despite the initial poor prognosis factors.
was noted. The developed leukocytosis while The absence of disseminated intravascular coagulation, a receiving ATRA was treated with hydroxyurea frequent complication in acute promyelocytic leukemia at 2.5g/day, hydration and allopurinol. Because onset was a particular feature of the case. ‰ of the leukemic medullar infiltration and Mædica A Journal of Clinical Medicine, Volume 2 No.4 2007 ACUTE PROMYELOCYTIC LEUKEMIA MICROGRANULAR VARIANT – A CLINICAL AND THERAPEUTICAL APPROACH REFERENCES
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