A recent case report published in Frontiers in Oncology describes an 81-year-old woman with high-risk mast cell leukemiaMast cell leukemia The most severe subtype of SM, caused by the rapid buildup of immature mast cells in the bone marrow and blood. Mast cell leukemia accounts for less than 5% of SM cases and has a poor prognosis., the rarest subtype of systemic mastocytosis (SM), caused by a very rare mutation in the KIT gene. The study emphasizes the importance of thorough diagnostic evaluation to identify uncommon presentations of SM.
The individual initially presented with persistent back pain and dizziness. Laboratory testing revealed 3% abnormally shaped white blood cells that raised suspicion for a mast cell diseaseMast cell disease A group of conditions in which mast cells behave abnormally by building up in excess, releasing chemicals too easily or both. Includes mastocytosis, mast cell activation syndrome and hereditary alpha-tryptasemia.. She also had severely low hemoglobin and platelets.
The most common mutation in SM is the D816V mutation in the KIT gene, in which the amino acid aspartic acid is replaced by the amino acid valine. This patient, however, had the KIT V559G mutation, where glycine replaces valine. The authors noted this mutation is extremely rare, with only one known prior case. She also had a complex immune marker and chromosomal profile, further complicating this case.
Bone marrow biopsyBone marrow biopsy A procedure to collect a sample of bone marrow using a needle. Often used to examine the characteristics of mast cells and diagnose SM. showed 69.5% abnormal bone marrow cells that were biochemically consistent with mast cells. Together with the confirmed KIT mutation, the patient met the diagnostic criteria for MCL. In particular, she was diagnosed with aleukemic MCL, meaning a very low proportion of abnormal mast cells were present in the bloodstream.
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Upon admission to the hospital, the patient developed several severe complications, including respiratory failure and sepsis. She received various anti-infective and anti-inflammatory medications.
After confirming the diagnosis of MCL, the patient began taking 100 mg imatinib orally once per day. Imatinib is a targeted therapy that blocks an abnormal protein found on cancer cells. She subsequently developed upper gastrointestinal bleeding, which the researchers attributed to a combination of imatinib and disease-related injury. Three days later, she experienced a heart attack.
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After careful monitoring and comprehensive care, the individual displayed significant improvements in clinical symptoms. Repeat testing of the bone marrow showed very few abnormal mast cells, indicating a positive response to therapy. At a four month follow-up appointment, she remained stable.
“This case highlights that for older patients with MCL with high-risk features and rare KIT mutations, treatment must be highly individualized,” the authors concluded. “A tailored therapeutic strategy should be employed to avoid aggressive regimens without clear benefits.”
