Leukemia - Acute
Recurrent genetic abnormalities
Microgranular variant of acute promyelocytic leukemia

Author: Syed Zaidi, M.D. (see Authors page)

Revised: 30 March 2018, last major update February 2013

Copyright: (c) 2001-2018, PathologyOutlines.com, Inc.

PubMed Search: Microgranular variant of acute promyelocytic leukemia

Cite this page: Zaidi, S. Microgranular variant of acute promyelocytic leukemia. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/leukemiamicroapl.html. Accessed August 17th, 2018.
Definition / general
  • Formerly called AML-M3v
  • Note: "variant" APL without further description may mean microgranular variant or an APL variant other than t(15;17)
  • Peripheral blood white blood count usually elevated, in contrast to hypergranular form
  • Diagnosis: cytogenetics recommended because other AML cases may appear similar (Am J Clin Pathol 2002;117:651)
Prognostic factors
  • Treatment with ATRA and anthracyclines recommended for APL
  • CD56 expression associated with less favorable prognosis
Case reports
Microscopic (histologic) description
  • Predominatly bilobed leukemic cells have fewer and smaller cytoplasmic granules, usually multiple Auer rods but less than classic (hypergranular) promyelocytic leukemia
  • Nuclei is folded, convoluted and markedly irregular
  • Microscopic (histologic) images

    Images hosted on PathOut server:
    Missing Image

    Promyelocytes have abundant fine
    azurophilic cytoplasm with variable
    size and basophilia, markedly
    lobulated and invaginated nuclei

    Missing Image

    Small hyperbasophilic promyelocytes
    with prominent cytoplasmic budding,
    most cells have sparsely granular
    cytoplasm and lobulated nuclei



    Images hosted on other servers:
    Missing Image

    Small hyperbasophilic promyelocytes
    with prominent cytoplasmic budding,
    most cells have sparsely granular
    cytoplasm and lobulated nuclei

    Positive stains
    Molecular / cytogenetics description
    Variant translocatios in acute promyelocytic leukemia:
    • A subset of cases which morphologically resemble APL and show variant translocation involving the RARA
    • Fusion partners include:
      • ZBTB16 (previously known as PZLF) on 11q23
      • NUMA1 (nuclear matrix associated gene1) on 11q13
      • NPM1 (nucleophosmin gene) at 5q35
      • STAT5B at 17q11.2
    Electron microscopy description
    • Stellate array of endoplasmic reticulum is characteristic
    Electron microscopy images

    Images hosted on PathOut server:
    Missing Image

    Smaller granules than hypergranular
    variant, granules are more
    uniform in size and endoplasmic
    reticulum is prominent

    Missing Image

    Small granules
    and stellate array
    of endoplasmic
    reticulum

    Differential diagnosis