Systemic mastocytosis: a rare cause of osteoporosis.

A 61-year old female patient who was referred to the endocrine clinic for evaluation of an elevated alkaline phosphatase. She was originally referred to gastroenterology (GI), however no GI causes of elevated alkaline phosphatase was found. Upon fractionation, it was noted that she had elevation in bone specific alkaline phosphatase. Past history was significant for hypertension, atrial fibrillation and menopause 6 years ago. She was also noted to have multiple drug allergies manifesting as urticaria and flushing. Review of the past records revealed a persistently elevated alkaline phosphatase over the last two years. She had no history of falls or fractures. Computed tomography (CT) abdomen done to rule out biliary pathology, revealed osteosclerotic and osteolytic lesion in the pelvis concerning neoplastic disease. Bone marrow biopsy however, was negative for cancer but consistent with systemic mastocytosis (SM). Dual Energy X-ray absorbimetery (DEXA) scan revealed osteoporosis Serum tryptase levels were elevated; further genetic analysis showed a positive CKIT D816 mutation. She was started on bisphosphonates (initially alendronate and then ibandronate). Upon follow up at two years she had not experienced any fractures and her bone mineral density also had improved significantly.