Bone mineral density in patients with systemic mastocytosis: correlations with clinical and histopathological features

Objective Systemic mastocytosis (SM) is a heterogeneous haematological entity characterised by proliferation of mast cells. Skeletal abnormalities of SM include osteolysis, osteopenia and osteoporosis but also osteosclerosis. A routinely used modality to assess bone density is dual-energy x-ray absorptiometry (DXA). The present study sought to elucidate possible associations between DXA findings with both clinical and bone marrow biopsy findings in SM. Methods Patient records of the local oncology and haematology department from 2007 to 2018 were screened for patients with SM. Overall, 39 patients (18 women and 21 men) with sufficient DXA images and clinical data were identified. We evaluated cKit mutation, tryptase level in serum, alkaline phosphatase, calcium level in serum, haemoglobin level, leucocytes and thrombocytes. Bone marrow biopsies were also evaluated. Results There were no significant differences between the different bone marrow patterns and in regard of cKit mutations. Significant lower bone mineral density (BMD) - T-score and Z-score values were identified for the indolent type compared to aggressive type. Correlation analysis revealed an association between BMD and tryptase level (r=035, p=0.049), mast cell proportion in bone marrow biopsy (r=0.45, p=0.01) and with the years since diagnosis (r=-0.42, p=0.02). Moreover, the correlations differed between the indolent and aggressive type. Conclusion DXA findings are associated with clinical and bone marrow biopsy parameters in SM. A positive association with tryptase level and mast cell amount in bone marrow biopsies was identified. This corroborates the usefulness o DXA in SM beyond the sole assessment of osteopenia and osteoporosis.