SAT-772 - Managing Systemic Mastocytosis-Associated Osteopenia in A Patient with Acute Myeloid Leukemia

Background: Systemic mastocytosis (SM) is characterized by clonal expansion and proliferation of neoplastic mast cells with accumulation in multiple organ systems, and bone involvement present in most SM cases. Mast cells not only contribute to inflammation and allergic reactions but also secrete an array of mediators that promote osteoclast formation and/or inhibit osteoblast activity. These mediators thus have a role in osteopenia, osteoporosis, osteoarthritis, often disproportionate to traditional risk factors. SM thus represents an underrecognized cause of secondary bone disease. Management is complicated when SM cooccurs with acute myeloid leukemia (AML), a rare but recognized association. SM with associated clonal hematological non-mast cell lineage disease represents 40% of cases.

Clinical

Case: A 79-year-old Caucasian female with a history of AML with SM with associated clonal hematological non-mast cell lineage disease presented to the endocrine team for evaluation of osteopenia. Patient was diagnosed with AML with SM 1.5 years prior to presentation following exertional dyspnea and weight loss of 15 lbs over 4 months. Bone marrow biopsy revealed AML with dysmegakaryocytes, dyserythropoiesis with ringed sideroblast, focal myelofibrosis, and SM. CT chest, abdomen and pelvis revealed innumerable tiny sclerotic foci throughout the bones without discrete measurable lesions prompting further bone health evaluation. Patient was initiated on Azacitidine/venetoclax by oncology team. Patient’s risk factors specific to bone health include age, postmenopausal status, history of hypothyroidism due to Hashimoto’s thyroiditis, stage 3A CKD, and low calcium intake lifelong. Family history is negative for osteoporosis and negative for hip fracture. Vitals revealed blood pressure of 104/74 mm Hg, heart rate of 122, BMI of 21.76 kg/m2. Physical exam was not performed. Laboratory tests revealed tryptase levels greater than 200 (≤10.9 ug/L), an alkaline phosphatase level of 67 (postmenopausal 14.2-42.7 U/L), and a Vit D, 25-Hydroxy level of 41 (≥30 ng/mL). Recent DXA revealed osteopenia of the lumbar spine (T-Score: -2.2, trabecular bone score: 1.226, BMD 0.921 g/cm2) and osteopenia of the hips (femoral neck T-score: -1.8, BMD: 0.792 g/cm2). Given the presence of osteopenia and the challenges of bone disease management in SM, denosumab is being considered as a potential next step to optimize bone health.

Conclusion: This case highlights the importance of SM as a clinically significant cause of secondary bone loss and underscores the importance of comprehensive bone health assessment in patients with concurrent hematologic malignancy. Recognition of mastocytosis-associated skeletal disease and selection of bone-directed therapy may be important in optimizing bone health outcomes.

*Unless otherwise noted, all abstracts presented at ENDO must not be released to the press or the public until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.*