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HLA‐DR Positive Acute Promyelocytic Leukemia (APL)
Author(s) -
Mendoza Alejandro S,
Qing Xin,
Dungo Maria,
Lasky Joseph,
Panosyan Eduard,
Cai Junchao
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.807.18
Subject(s) - immunophenotyping , acute promyelocytic leukemia , pathology , cd117 , medicine , bone marrow , cd34 , leukemia , myeloid leukemia , myeloid , acute leukemia , hla dr , immunology , biology , flow cytometry , antigen , stem cell , retinoic acid , biochemistry , genetics , gene
BACKGROUND Acute promyelocytic leukemia (APL) with t(15;17)(q22;q21)/PML‐RARα is a subtype of acute myeloid leukemia(AML) with distinct morphologic and immunophenotypic characteristics. It is a highly aggressive disease that requiresrapid diagnosis and early intervention. Compared with other types of AML, APL typically displaysa triad of absent or weak CD34, absent HLA‐DR, and positive CD117. HLA‐DR positive APL is extremely rareand its clinical and pathological features have not been reported. A total of 45 cases of APL with t(15,17)/PMLRARα were diagnosed at Harbor‐UCLA Medical Center from year 2006 to 2015. Among them, only two cases were positive for HLA‐DR by flow cytometry immunophenotyping. Here we describe the clinical, morphologic, immunophenotypic, and cytogenetic features of these two cases. RESULTS AND DISCUSSION The patients in both cases presented with anemia, thrombocytopenia, and decreased WBC count. In case A, the peripheralblood smear showed many myeloblasts and only occasional abnormalpromyelocytes. Although a thin Auer rod was found in rare blasts, neitherthe thick Auer rods that typically seen in APL nor faggot cells were identified. While case B showed characteristic morphologic features of hypergranular variant of APL in the bone marrow, no blasts orabnormal promyelocytes were identified in the peripheral bloodsmear. Therefore, APL should not be excluded even when abnormalpromyelocytes are not present in the peripheral blood smears. In addition, MPO cytochemical stain performed on the bone marrow aspiratesmear of case A did not show uniform strong staining pattern that is commonly observed in APL. Besides HLA‐DR, CD34 was also expressed on the blasts of case A. These atypical morphologic and immunophenotypic features may be attributed to the additional cytogenetic abnormalities found in case A. CONCLUSION HLA‐DR‐positive APL is very rare and represents about 4% of all APL cases in our study. Due to its rare occurrence, continuous reporting of HLA‐DR positive APL will bring to the awareness of the broad clinical and pathological spectrum of APL, provide better clinicopathologic correlation, and facilitate rapid diagnosis and thus promptinitiation of appropriate management of this aggressive malignant tumor. Support or Funding Information We declare no benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.