Acute promyelocytic leukemia toluidine blue subtype

Rosangela Invernizzi, Angela Maria Iannone, Stefano Beknuzzi, Andrea d'alessio, Cristina Fiamenghi, Carla Fenoglio, Angela Rossi, Gaetano Bergamaschi, Edoardo Ascari

Research output: Contribution to journalArticlepeer-review


In the hypergranular group of acute promyelocytic leukemia (APL) a rare subvariant with basophilic granules, metachromatic for toluidine blue, is recognizable. To evaluate the incidence as well as the biological and clinical significance of this subtype, we studied 53 consecutive untreated patients with APL with morphological, cytochemical, immunological and cytogenetic methods. In 10 cases (19% of the total) granules stained metachromatically in percentages of promyelocytes ranging from 16 to 60. In these cases peroxidase positivity was weaker than in the classic hypergranular and micro-granular M3 and activities of esterases were usually present; at the ultrastructural level granules contained particulate material. Immunophenotypic and cytogenetic characteristics seemed not to differ from those of other M3 cases. Coagulopathy was usually life-threatening, notwithstanding the low white cell count, and the median survival was short. Hyperhistaminemia-related symptoms were not observed. Cytochemical, immunologic and cytogenetic findings are useful to differentiate this form from M2 with basophilic differentiation and from mast cell leukemia.

Original languageEnglish
Pages (from-to)57-60
Number of pages4
JournalLeukemia and Lymphoma
Issue numberS1
Publication statusPublished - 1995


  • Acute promyelocytic leukemia
  • Basophilic leukemia
  • Cytochemistry
  • Cytogenetics

ASJC Scopus subject areas

  • Hematology
  • Oncology
  • Cancer Research


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