SAT-718 Systemic Mastocytosis Presenting as Recurrent Vertebral Compression Fractures

Abstract Disclosure: G. Schmidt: None. T.D. Hoang: None. Background: Systemic mastocytosis is a rare but underrecognized cause of secondary osteoporosis and fragility fractures. Clinical Case: A 56-year-old man presented for history of multiple vertebral compression fractures. Six years prior to presentation (2016) the patient experienced sudden onset mid-back pain while jumping on a trampoline, and subsequent imaging evaluation noted a T7 vertebral compression fracture. He underwent limited diagnostic work-up at the time, but based on symptoms of hot flashes, fatigue, and decreased strength and muscle mass and a single midday low total testosterone reading, his physician started him on testosterone replacement therapy. Approximately one year later, the patient experienced sudden worsening of his thoracic back pain and repeat radiographic evaluation noted a new T11 compression fracture. He denied any history of falls or trauma in the intervening time period since his last x-ray less than 1 year prior. At this time he started ibandronate for one year before transitioning to risendronate for a total treatment duration of 2 years before discontinuation for unclear reasons. Despite subsequent consistent use of testosterone, and normalization of testosterone levels, the patient continued to experience hot flashes. The patient suffered a fall from standing height experiencing acute onset lumbar back pain. Imaging revealed a new L2 compression fracture. He underwent kyphoplasty followed by a posterior lumbar fusion from L1 through L5. Broad evaluation for causes secondary osteoporosis was unrevealing. The patient received multiple short courses of glucocorticoids for low back pain in the past decade but otherwise no other concerning history for secondary causes of osteoporosis was elicited initially. On further review, however, collateral information from the patient’s wife revealed flushing associated with his “hot flashes” as well as closer review of labs noted long-standing mild eosinophilia. Therefore, a tryptase level was drawn and noted to be elevated on three separate occasions. After referral to immunology the patient underwent bone marrow biopsy which confirmed the diagnosis of smoldering systemic mastocytosis (SSM). The patient since completed a course of teriparatide and most recently started treatment with zoledronic acid. Patient enrolled in a clinical trial for treatment of SSM with an investigational drug. Conclusion: Systemic mastocytosis is a rare but underrecognized cause of secondary osteoporosis and fragility fractures. Screening with serum tryptase should be considered in an adult with osteoporosis and pathologic bone fractures if no other risk factors for osteoporosis are identified or if other complementary features are present. Presentation: Saturday, July 12, 2025