THU431 An Interesting Case Of Severe Osteoporosis In A Young Male

Disclosure: M. Bilbatua: None. M. Deshmukh: None. Background: Systemic Mastocytosis is a rare disorder in which Osteoporosis is seen in about 24% of cases. We describe a rare case of Secondary Osteoporosis in a young man caused by Systemic Mastocytosis. Case presentation: A 32-year-old male with no significant medical history was seen by Endocrinology for evaluation of Osteoporosis. Symptoms started after two episodes of falls which caused persistent pain. A CT scan of thoracic spine revealed chronic anterior wedge compression fracture of T5, T7 and T10 with approximately 5-10% loss of height. DEXA scan demonstrated T-score of -4.2 at L1-L4, T-score of -2.3 at left hip suggestive of severe Osteoporosis. The patient admitted to generalized flushing and itching after taking hot showers as well as intermittent episodes of palpitations. The patient was started on Calcitonin nasal spray daily for pain related to vertebral fracture. Testing for secondary causes of Osteoporosis showed a Total testosterone 410 ng/dL (250-1,100 ng/dL), PTH 16 pg/mL (16 - 77 pg/mL), TSH 1.88 mIU/L (0.40 - 4.50 mIU/L), Phosphorus 4.1 mg/dL (2.5 - 4.5 mg/dL), Magnesium 2 mg/dL (1.5 - 2.5 mg/dL), Alkaline phosphatase 66 U/L (36 - 130 U/L), Vitamin D 25 ng/mL (30 - 100 ng/mL), Calcium 9.3 mg/dL (8.6 - 10.3 mg/dL), Tryptase 64 mcg/L (<11.0 mcg/L), 5-HIAA 24H Ur mg/24H 3 (<=6.0 mg/24 h). Based on this, the patient was seen by Hematology/Oncology for evaluation on elevated tryptase levels. Bone marrow biopsy and aspirate was performed, demonstrating 20% Mast cells positive for CD 117, CD 25, patient was diagnosed with Mastocytosis and treatment with Midostaurin 100 mg PO twice daily and Zometa every 12 weeks was initiated. Improvement of Tryptase was noted within two months of treatment. Discussion: Systemic Mastocytosis is a rare disease often complicated by Osteoporosis of which around 37% of the patients will develop Osteoporotic fractures where Bisphosphonates are effective and have a role in the associated refractory bone pain. The pathophysiological mechanisms leading to osteoporosis in Systemic Mastocytosis are not well understood. Although rare, back pain secondary to osteoporotic vertebral fractures is often the major presenting symptom of Mastocytosis and it should be included in the differential diagnosis of idiopathic osteoporosis due to its significant morbidity. Presentation: Thursday, June 15, 2023