Clinical Report: Aleukemic Mast Cell Leukemia Featuring KIT p.V559G Mutation

Overview

This case report describes an 81-year-old woman with aleukemic mast cell leukemia (MCL) characterized by a rare KIT p.V559G mutation and a CD25-negative immunophenotype. The patient experienced severe complications.

Background

Mast cell leukemia (MCL) is the most aggressive form of systemic mastocytosis and is often associated with poor prognosis. The majority of MCL cases are driven by the KIT p.D816V mutation, while other noncanonical mutations, such as p.V559G, are less understood.

Data Highlights

No numerical data or trial data available in the source material.

Key Findings

• The patient had severe pancytopenia with 3% atypical mast cells in peripheral blood.
• Bone marrow examination revealed 69.5% abnormal mast cells.
• Flow cytometry showed a unique immunophenotype: CD117bri, CD9bri, CD203c+, CD2+, CD25-, and HLA-DR-.
• Karyotyping indicated complex clonal abnormalities, including monosomy 7.
• A rare KIT p.V559G mutation was identified with a variant allele frequency of 42%.

Clinical Implications

This case highlights the need for integrated diagnostic approaches in older patients with MCL, particularly those with rare mutations and complex cytogenetics.

Conclusion

This case enriches the understanding of MCL's molecular spectrum.

Related Resources & Content

1. Frontiers | Case Report: Aleukemic Mast Cell Leukemia with KIT p.V559G Mutation, CD25-Negative Immunophenotype, and Complex Karyotype
2. Diagnosing Systemic Mastocytosis: State of the Art - PMC
3. Blood Cancer Journal — Next-generation sequencing with a myeloid gene panel in core-binding factor AML showed KIT activation loop and TET2 mutations predictive of outcome
4. Frontiers in Oncology — Case Report: Experience of a rare case of primary acute mast cell leukemia with FGFR1 gene rearrangement
5. Blood Cancer Journal — Multi-Omics Analysis of Three Hematological Cancers in a Patient Identifies Their Origin from Clonal Hematopoietic Stem Cells
6. Blood Cancer Journal — Significance of KIT exon 17 mutation depends on mutant level rather than positivity in core-binding factor acute myeloid leukemia
7. Diagnosing Systemic Mastocytosis: State of the Art - PMC
8. Frontiers | Case Report: Aleukemic Mast Cell Leukemia with KIT p.V559G Mutation, CD25-Negative Immunophenotype, and Complex Karyotype
9. Efficacy and safety of avapritinib in advanced systemic mastocytosis: 4-year follow-up of the PATHFINDER study - PMC