| Abstract|| |
Acute promyelocytic leukemia (APML) is a well-characterized malignancy with typical clinico-hematological and molecular features. However, Indian data on this malignancy are limited. This study was conducted to determine the clinico-hematological profile of APML in India. Thirty-five patients with APML presenting to Hematology Department, AIIMS, New Delhi, between July 2003 and June 2005 were evaluated for presenting clinical features, hemogram, peripheral smear, bone marrow morphology and cytochemistry. Reverse transcriptase PCR (RT-PCR) for PML-RARα was done in all cases. Male-to-female ratio was 0.9:1 (males - 17 and females - 18) with median age 25 years (range 11-57 years). Presenting features included anemia, bleeding, fever, gum hypertrophy and scrotal ulceration. All cases showed hypergranular abnormal promyelocytes. Median hemoglobin was 6.3 g/dL (range - 3.0-9.0 g/dL), total leukocyte count (TLC) was 33.88 × 10 9 /L (range - 1-170 × 10 9 /L). Platelet count was 28 × 10 9 /L (range - 4-170 × 10 9 /L). All cases were positive for myeloperoxidase and sudan black (SB), whereas 60% cases also showed non specific esterase (NSE) positivity with 40% cases being fluoride sensitive. RT-PCR showed PML-RARα in 33/35 cases with the bcr3 isoform being present in 24/33 positive cases (72.7%). The two cases negative for PML-RARα showed typical morphology and responded to ATRA. On statistical analysis, no correlation was found between bcr isoform and TLC, platelet count, age sex and early death. Unusual features included gum hypertrophy and scrotal ulceration at presentation and high median presenting TLC (33.8 × 10 9 /L). There was, however, no microgranular variant. Another interesting feature was a high incidence of NSE positivity (60%), which was fluoride sensitive in 40%. Moreover, the bcr3 isoform was significantly overexpressed (72.7%) in comparison to other studies. APML in India has certain unusual features, which may reflect a different biology.
Keywords: Acute promyelocytic leukemia, biology, India, reverse transcriptase-PCR
|How to cite this article:|
Dutta P, Sazawal S, Kumar R, Saxena R. Does acute promyelocytic leukemia in Indian patients have biology different from the West?. Indian J Pathol Microbiol 2008;51:437-9
|How to cite this URL:|
Dutta P, Sazawal S, Kumar R, Saxena R. Does acute promyelocytic leukemia in Indian patients have biology different from the West?. Indian J Pathol Microbiol [serial online] 2008 [cited 2018 Aug 15];51:437-9. Available from: http://www.ijpmonline.org/text.asp?2008/51/3/437/42555
| Introduction|| |
Acute promyelocytic leukemia (APML) is a well-characterized malignancy with typical clinical, hematological, morphological and molecular features. The history is usually short with bleeding a prominent feature. Most cases present with pancytopenia and atypical promyelocytes. Almost 30% cases constitute agranular or hypo-granular variant. The abnormal cells show strong myeloperoxidase (MPO) and SB positivity with few cases showing NSE positivity, which is usually fluoride-resistant. Molecular studies reveal the fusion transcript PML-RARα and depending on the breakpoint in chromosome 15 within PML intron, the isoform may be short (bcr3) or long (bcr1). The present study was conducted to determine the clinico-hematological profile of APML patients in India.
| Materials and Methods|| |
Acute promyelocytic leukemia patients presenting to the Department of Hematology, All India Institute of Medical Sciences, New Delhi over a time period of 24 months (July 2004-June 2005) were taken up for the study. The clinical features presenting hematological parameters, morphology were analyzed. Peripheral blood and bone marrow smears were stained by Jenner's Giemsa and cytochemistry consisted of MPO, SB and NSE with fluoride testing using standard reagents and methods.  For molecular studies, bone marrow/peripheral blood samples were collected. Reverse transcriptase PCR (RT-PCR) was done for the PML-RARα fusion transcript. For RT-PCR, RNA was extracted and reversely transcribed using random hexamers. The quality of c-DNA was assessed by amplification of beta-2 microglobulin gene. RT-PCR was done as described previously by nested primers and presence of fragment sizes of 355 bp for bcr3, 685 bp for bcr1 and 585 bp for bcr2 were considered positive for PML-RARα [Figure 1].  Patients were grouped into various risk groups according to the following criteria: high risk - total leukocyte count (TLC) > 10 × 10 9 /L and platelet count < 40 × 10 9 /L; intermediate risk - TLC > 10 × 10 9 /L and platelet count > 40 × 10 9 /L; and low risk - TLC < 10 × 10 9 /L, any platelet count.
| Results|| |
Thirty-five cases of APML (17 males, 18 females and male-to-female ratio = 0.94:1) were studied. The median age was 25 years (range 11-57 years) and 71% were within 30 years of age [Table 1]. The duration of symptoms was as short as 2 days to as long as 30 days with a median of 23 days. The presenting clinical features are given [Table 2].
The median hemoglobin at presentation was 6.3 g/dL (range 3.0-9.0 g/dL). The TLC ranged from 1 × 10 9 /L to 170 × 10 9 /L with a median of 33.88 × 10 9 /L. The median platelet count was 28 × 10 9 /L with a range of 4-170 × 10 9 /L. All cases showed abnormal hypergranular promyelocytes. Cytochemistry reports were available in 28 cases. All cases showed strong SB and MPO positivity. In addition, 15 (60%) also stained with NSE of which 10 (40%) showed sensitivity to fluoride. On risk stratification, eight cases were in the high-risk group (22.85%), nine were in the intermediate-risk group (25.71%), whereas 18 were in the low-risk category (51.4%).
Molecular studies revealed PML-RARα positivity in 33 out of 35 cases. However, both the negative cases also showed typical morphology and good response to ATRA. On analysis of fusion transcript sizes, it was seen that the short or bcr3 isoform was overexpressed. Bcr3 was seen in 24 out of the 33 positive cases (72.7%), whereas bcr1 was found in nine cases. Of the total of 35 cases, 10 patients died within 48 h of hospital administration (early deaths). An attempt was made to see if there was any correlation between the risk category and age, sex, duration of symptoms and early death. The Chi-square test revealed a direct correlation of the risk category and early death with most of the early deaths occurring in the high- and intermediate-risk groups ( P -value = 0.012).
No correlation was found between bcr isoform and TLC, platelet count, age, sex, duration of illness, risk category of the patient and between the bcr isoform and early death or the day 28 remission status. No statistical relationship was found between platelet count, duration of symptoms and occurrence of early deaths. However, there was a direct relationship between the TLC and occurrence of early death with most deaths occurring in patients with higher presenting TLC ( P -value = 0.037).
| Discussion|| |
On examination, two unusual features were gum hypertrophy and scrotal ulceration. Two patients had gum hypertrophy at presentation. Generally, gum hypertrophy is very rarely seen in AML-M3.  A 17-year-old boy had scrotal ulceration at presentation itself. Cultures grew E. coli and a diagnosis of Fournier's gangrene was given from Surgery and Dermatology Departments, respectively. Fournier's gangrene is a reported complication of ATRA therapy, but in this young boy it was seen even before the start of ATRA. Another unusual finding was a high TLC at presentation. The TLC varied from 1 × 10 9 /L to 170 × 10 9 /L with a median of 33.8 × 10 9 /L. This is rather unusual as APML is characterized by pancytopenia in peripheral blood. Raised TLC is seen in 10-30% cases, especially with the microgranular variant.  However, there was no such association in the present series.
All the 35 cases had typical morphology and there was no case with microgranular or hypogranular promyelocytes. Even the cases with high TLC had predominance of hypergranular promyelocytes. This is also rather unusual as some series report the microgranular variant of APML with a frequency as high as 20-30%.  Cytochemistry details were available for 28 cases. As expected, all the cases showed strong positivity for MPO and SB but interestingly, 60.7% (17/28) of the cases also showed positivity for NSE. Even more unusual was the fact that quite a large percentage (39.2%, 11/28) also showed sensitivity to fluoride. Liso et al.  found non-specific esterase positivity in two cases out of a total of five. In another study involving 43 patients of APML, 12 (27.9%) were positive for non-specific esterase, about half of them also showing fluoride sensitivity. Gupta et al.  found an NSE positivity of 13.5% (5/37) with all the cases showing fluoride sensitivity as well. Thus, the present study has found a very high incidence of NSE positivity along with fluoride sensitivity as compared to previous reports.
Reverse transcriptase-PCR done at the time of diagnosis revealed 33 out of the 35 cases to be positive for the PML-RARα transcript. Two cases were negative for the fusion transcript, but both of them had classical morphology and also responded to ATRA. An unusual feature was the increased expression of bcr3 isoform, which was seen in 24 cases (72.7%). The incidence of bcr3 has been reported to be much less in Western studies.  This particular feature has already been reported.  No significant correlation was found between the bcr isoform and presenting TLC, platelet count, age, sex, duration of presenting symptoms, or any other variable. This is similar to the findings of Grimwade et al. ,  who in a series of 93 patients, did not find a correlation between bcr subtype and age, sex, etc. and other disease parameters including the presenting TLC. Similarly, Douer et al.  did not find any such association. This is unlike reports of several workers who report an association of high TLC at presentation and bcr3 isoform. Lo-Coco et al.  reported that patients with bcr3 isoform had higher TLC and associated microgranular variant. On the other hand, some studies  reported higher WBC counts associated with the variable isoform, i.e., bcr2. However, in the present study, there was no association of any disease feature including the presenting TLC with bcr isoforms.
| Conclusion|| |
Thus, APML patients in India have certain unique features such as gum hypertrophy, high TLC at presentation, a high incidence of NSE positivity including fluoride sensitivity and an overexpression of bcr 3 isoform, which may reflect a unique biology.
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Department of Haematology, All India Institute of Medical Sciences, New Delhi - 110 029
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2]