The Prevalence Of Osteoporosis Is Low in Adult Cutaneous Mastocytosis Patients

Abstract

BackgroundSystemic mastocytosis (SM) is a clonal disorder of mast cells frequently associated with vertebral osteoporosis (OP) and subsequent vertebral fractures. The natural history of this OP remains unclear. Importantly, we do not know whether OP represents an early event triggered alongside mast cell abnormalities, and whether mast cell clonality is sufficient to trigger osteoporosis. ObjectiveTo describe OP in patients with medullar clonality in cutaneous mastocytosis (CM) and monoclonal mast cell activation syndrome (MMAS) and to compare their osteoporosis characteristics to those of non-advanced SM patients (bone marrow mastocytosis (BMM) and indolent systemic mastocytosis (ISM)). MethodsWe retrospectively analyzed clinical, biological and densitometric data of 27 CM, 13 MMAS and 135 SM patients from the mastocytosis expert center (CEREMAST) in Toulouse. ResultsOP (respectively 3.7, 30.8 and 34.1%) and vertebral fractures (0.0, 15.4 and 20%) were less frequent in CM compared to MMAS and SM, despite the presence of clonal mast cells in the bone marrow. Most patients with OP and vertebral fractures in the non-SM groups had the usual risk factors for OP. Interestingly, the only non-SM patient with a typical SM-like OP had high bone marrow tryptase, developed bone marrow KIT mutation during follow-up, and had a family history of SM. Our data show that OP is not a common clinical finding in CM but is frequent in MMAS. When OP and fractures occur in CM and MMAS patients, they differ from the usual phenotype of SM bone fragility. ConclusionOur findings suggest that in most CM patients, the meaning and management of OP differs from that of OP in MMAS and non-advanced SM. Prospective longitudinal studies and the validation of predictors are needed to identify CM and MMAS patients developing SM-related OP.