To enrich the molecular spectrum of mast cell leukemia (MCL) and emphasize the value of integrated diagnosis.
Approach:
Clinical Data: An 81-year-old woman presented with dizziness and back pain, with severe pancytopenia and atypical mast cells in peripheral blood.
Laboratory Examinations: Complete blood count showed significant abnormalities including low hemoglobin and platelet counts, with elevated lactate dehydrogenase.
Bone Marrow Examinations: Bone marrow analysis revealed hypercellularity with a predominance of abnormal mast cells, characterized by specific immunophenotypic features.
Cytogenetic and Molecular Biological Examinations: Cytogenetic analysis indicated complex clonal abnormalities, and next-generation sequencing identified a rare KIT p.V559G mutation.
Key Findings:
The patient had a rare activating KIT p.V559G mutation with a variant allele frequency of 42%.
Flow cytometry revealed a unique immunophenotype: CD117bri, CD9bri, CD203c+, CD2+, CD25-, and HLA-DR-.
Karyotyping showed complex clonal abnormalities including monosomy 7.
Interpretation:
This case highlights the importance of comprehensive diagnostic workup in aleukemic MCL and the potential for individualized low-intensity targeted therapy in older patients.
Limitations:
Long-term survival benefit of the treatment remains unproven.
The rarity of the case limits generalizability.
Conclusion:
This case represents a rare instance of aleukemic MCL with unique genetic and immunophenotypic features.
