APL(Acute promyelocytic leukemia) (AML M3):

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 Either hypergranular or microgranular / hypogranular, 5 - 8% of AML cases.Median age 35 - 40 years but can occur at any age. Decreased WBC count (hypergranular variant) at presentation with abnormal promyelocytes.Usually disseminated intravascular coagulation (DIC) and hemorrhage before or during induction chemotherapy, which may cause early death. Rarely organomegaly, extramedullary disease, skin involvement. Criteria for diagnosis: most cells (> 50%) are abnormal promyelocytes with heavy cytoplasmic granulation that may obscure the nuclear cytoplasmic margin, often reniform or bilobed nucleus; cells with multiple Auer bodies usually present; also bundles of Auer rods ("faggot cells" - resembles bundle of sticks). Note: if t(15;17) present, diagnose as AML even if initial blast count is < 20%

Prognostic factors-In children, age < 10 years is favorable. Survival: excellent if DIC and hemorrhage are adequately controlled; excellent in adults with complete remission.  flow cytometry is not diagnostic for APL, and must be confirmed with retinoic acid receptor-alpha (RARα) :     

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Immunphenotyping:

Positive for CD9, CD11a and CD11b, Bright and heterogenous espression (CD2 (23%), CD13, CD33, CD64 (27%)), myeloperoxidase (strong) and HLA-DR (9%), Variable CD34, CD71 and CD99 while Negative for CD11b (but post-treatment is positive), CD11c, CD14, CD36, CD41, CD61, CD18(some time dim expression) and glycophorin A

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                                                                                                   CASE 1(HYPERGRANULAR)

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HYPERGRANULAR APL SHOWS: Blast(red) and lymphocytes(green). blasts are positive for CD9+, CD4+, CD11b+, CD13+, CD33+, CD15+, CD123+,CD14+,CD64+CD45+, CD38+ WHILE CD117-, CD15-, CD2-, CD19-, HLA-DR-,CD56-, CD18-.Pink color population is basophils

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                                                                                     CASE 2(HYPERGRANULAR)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

HYPERGRANULAR APL SHOWS: Blast(red) and lymphocytes(green). blasts are positive for CD9+, CD4+, , CD11b+, CD13+, CD33+, CD15+, CD123+,CD14+,CD64+CD45+,CD15dim,  while negative for  CD117-, CD2-, CD19-, HLA-DR-,CD56-,CD38-, CD18-. Pink color population is basophils

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                                                                            CASE 3(HYPOGRANULAR)

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HYPOGRANULAR APL SHOWS: Blast(red) and lymphocytes(green). blasts are positive for CD9+, CD4+, CD11b+, CD13+, CD33+, CD25+, CD123+,CD14+,CD64+CD45+,CD15dim, CD117dim while negative for CD2-, CD19-, HLA-DR-,CD56-,CD38-, CD18-, CD15-, CD36-, CD7- .

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REFERENCE:

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• Fang Xu, Chang-Xin Yin, Chun-Li Wang, et al., “Immunophenotypes and Immune Markers Associated with Acute Promyelocytic Leukemia Prognosis,” Disease Markers, vol. 2014, Article ID 421906, 6 pages, 2014. https://doi.org/10.1155/2014/421906.

• E. I. Ahmad, H. Akl, M. E. Hashem, and T. A. M. Elgohary, “The biological characteristics of adult CD34+ acute promyelocytic leukemia,” Medical Oncology, vol. 29, no. 2, pp. 1119–1126, 2012. View at Publisher · View at Google Scholar · View at Scopus

• F. Albano, A. Mestice, A. Pannunzio et al., “The biological characteristics of CD34+ CD2+ adult acute promyelocytic leukemia and the CD34- CD2- hypergranular (M3) and microgranular (M3v) phenotypes,” Haematologica, vol. 91, no. 3, pp. 311–316, 2006. View at Google Scholar · View at Scopus

• K. Kaito, T. Katayama, H. Masuoka et al., “CD2+ acute promyelocytic leukemia is associated with leukocytosis, variant morphology and poorer prognosis,” Clinical and Laboratory Haematology, vol. 27, no. 5, pp. 307–311, 2005. View at Publisher · View at Google Scholar · View at Scopus

• P. Montesinos, C. Rayón, E. Vellenga et al., “Clinical significance of CD56 expression in patients with acute promyelocytic leukemia treated with all-trans retinoic acid and anthracycline-based regimens,” Blood, vol. 117, no. 6, pp. 1799–1805, 2011. View at Publisher · View at Google Scholar · View at Scopus

• S. S. Yu and W. T. Zheng, 2010. View at Publisher · View at Google Scholar

• P. Lin, S. Hao, L. J. Medeiros et al., “Expression of CD2 in acute promyelocytic leukemia correlates with short form of PML-RARα transcripts and poorer prognosis,” American Journal of Clinical Pathology, vol. 121, no. 3, pp. 402–407, 2004. View at Publisher · View at Google Scholar · View at Scopus

• W. Gorczyca, “Acute promyelocytic leukemia: four distinct patterns by flow cytometry immunophenotyping,” Polish Journal of Pathology, vol. 63, no. 1, pp. 8–17, 2012. View at Google Scholar · View at Scopus

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