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Published on: February 21, 2018
Microgranular acute promyelocytic leukemia: a proposed role for a greater deformability of the leukemic cell
1Centre d'Hématologie et d'Immunologie Clinique, Hôpital du Saint-Sacrement, Laval, Québec, Canada.
Abstract:
A case of microgranular acute promyelocytic leukemia (APL), M-3 variant, is reported in a boy aged 5 years. The disease, which was rapidly fatal, presented with acute disseminated intravascular coagulation (DIC) and leukocytosis. Different cytomorphologic subtypes of promyelocytes were identified on the basis of cytoplasmic granular patterns: the microgranular type with barely visible cytoplasmic granulations and deeply basophilic cytoplasm and the more characteristic type with large promyelocytes containing azurophil granules. We observed a ratio of large promyelocytes to microgranular promyelocytes of 1:1.2 in the marrow and 1:4 in the peripheral blood. To explain this discrepancy, we hypothesize that the microgranular promyelocytes may be more deformable than the typical promyelocyte and that this intrinsic cellular characteristic may promote marrow egress and increase the likelihood of hyperleukocytosis in the M-3 variant.
Insights
This case study details a rapidly fatal microgranular acute promyelocytic leukemia (APL) in a child, presenting with disseminated intravascular coagulation. Researchers hypothesize microgranular promyelocytes
Area of Science:
- Hematology
- Oncology
- Cell Biology
Background:
- Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia.
- The M-3 variant of APL is characterized by specific cytomorphologic features.
- Understanding APL subtypes is crucial for diagnosis and treatment.
Observation:
- A rare case of microgranular acute promyelocytic leukemia (APL), M-3 variant, in a 5-year-old boy.
- The patient presented with rapidly fatal disseminated intravascular coagulation (DIC) and leukocytosis.
- Distinct promyelocyte subtypes were identified based on cytoplasmic granulation: microgranular and characteristic large forms.
Findings:
- A significant discrepancy in the ratio of microgranular to large promyelocytes was observed between bone marrow (1:1.2) and peripheral blood (1:4).
- Hypothesis: Microgranular promyelocytes exhibit increased deformability compared to typical promyelocytes.
- This cellular characteristic may facilitate marrow egress, contributing to hyperleukocytosis in the M-3 variant.
Implications:
- The findings suggest a potential mechanism for hyperleukocytosis in APL M-3 variant.
- Increased understanding of microgranular promyelocyte behavior may inform prognostic assessments.
- Further research into APL cellular deformability could reveal novel therapeutic targets.
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