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Acute promyelocytic leukemia with the pseudo-Chediak-Higashi anomaly and molecular documentation of t(15;17)
P H Symes1, M E Williams, H C Flessa
1University of Cincinnati College of Medicine, Department of Internal Medicine, Ohio.
Abstract:
Two morphologic variants of acute promyelocytic leukemia (AML M3) are recognized--the hypergranular form, in which Auer rods are usually numerous; and the microgranular form. The case of AML M3 reported here lacked numerous Auer rods but was hypergranular and demonstrated prominent giant Chediak-Higashi-like granules in the leukemic cells. Although routine karyotypic studies were inconclusive, at t(15;17) translocation was documented using Southern blot genotypic analysis and probes for the retinoic acid receptor-alpha and pml genes. This is the first case of this unusual morphologic anomaly in which the granules are described in routine histologic sections and the first with evidence of a t(15;17) chromosomal translocation. It also illustrates the importance of Southern blot analysis in suspected cases of AML M3 with "negative" karyotypic studies.
Insights
This study reports a rare hypergranular acute promyelocytic leukemia (AML M3) case with unusual granules. Southern blot analysis confirmed the characteristic t(15;17) translocation, crucial for diagnosis when routine karyotyping is inconclusive.
Area of Science:
- Hematology
- Oncology
- Molecular Genetics
Background:
- Acute promyelocytic leukemia (AML M3) presents with distinct morphologic variants, including hypergranular and microgranular forms.
- Diagnosis typically relies on morphologic assessment and cytogenetic analysis, particularly the t(15;17) translocation.
Observation:
- A unique case of AML M3 presented with hypergranularity and prominent giant Chediak-Higashi-like granules, but lacked numerous Auer rods.
- Routine karyotypic studies for this case were inconclusive.
Findings:
- Southern blot genotypic analysis definitively identified the hallmark t(15;17) chromosomal translocation using specific gene probes.
- This is the first documented instance of this specific morphologic anomaly with described giant granules in routine histology and confirmed t(15;17) translocation.
Implications:
- Highlights the diagnostic utility of Southern blot analysis in AML M3 cases with atypical morphology or inconclusive karyotyping.
- Underscores the importance of advanced molecular techniques for accurate diagnosis and classification of hematologic malignancies.
- Emphasizes the heterogeneity within AML M3 subtypes and the need for comprehensive diagnostic approaches.