A case study presented at the Society of Hematologic Oncology Annual Meeting involving an elderly man with 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. (MCL) highlights the diagnostic challenges of systemic mastocytosis (SM), particularly when the disease first appears as unexplained bone fractures and lesions that resemble metastatic cancer.
The first signs of SM can vary widely, making diagnosis challenging. When mast cells accumulate in the skeletal system the disease can cause fractures and lytic bone lesions. Because these findings can resemble those seen with metastatic cancer, the right diagnosis can be delayed.
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The case involved a 75-year-old man with hypertension who was referred to an oncology clinic after experiencing repeated hip fractures. Magnetic resonance imaging (MRI) revealed suspicious areas of bone destruction that made doctors wonder if he might have an underlying malignancy.
Further evaluation, including a 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 layers of tumor cells with a large number of eosinophils, a type of white blood cell important in the immune system. This suggested he had a mast cellMast cell A type of white blood cell produced in the bone marrow. They help defend against infections and play a key role in allergic reactions. In SM, mast cells become overactive and build up throughout the body. neoplasm — a type of disease where mast cells accumulate, such as SM. His serum tryptaseTryptase A protein enzyme that is primarily produced by mast cells and stored in small pockets within the cells, known as granules. High levels of tryptase are a key indicator of SM. level was markedly elevated, at 379 ng/mL — another sign seen with SM. Immunohistochemical testing of the lesion was positive for CD117, a marker expressed by mast cells, along with eosinophilic infiltrates.
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Additional molecular testing did not identify several mutations or genetic abnormalities that can be associated with mast cell or other blood cancers. Testing for the c-KIT D816V mutation, BRAF mutations, FIP1L1/CHIC2/PDGFRA abnormalities and PDGFRB rearrangements was negative. Serum protein electrophoresis was also negative.
The patient received one dose of cladribine (a chemotherapy drug that destroys abnormal white blood cells) followed by one week of treatment with midostaurin. During treatment, his hemoglobin dropped to 9 g/dL, prompting treatment to be temporarily withheld.
The patient’s extensive multisystem involvement indicated a poor prognosis, and his family was counseled about the expected disease progression and outcomes.
“This case emphasizes the importance of considering SM with MCL in elderly patients presenting with recurrent pathological fractures or unexplained lytic bone lesions,” the authors concluded. They emphasized that bone marrow examination, serum tryptase testing, immunohistochemistry and molecular studies can help establish the diagnosis and guide treatment.
