Abstract
Purpose Systemic mastocytosis (SM) is characterized by a clonal proliferation of neoplastic mast cells (MCs) in one or more extracutaneous organs including the bone marrow (BM). SM is often associated with osteoporosis (OP) and fractures. Hypertryptasemia usually occurs in SM. We investigated the prevalence of hypertryptasemia in a series of severe osteoporotic patients, the performance of the tryptase test in diagnosing SM in these patients, and their bone features. Methods The medical records of 232 patients (168 females and 64 males) with a diagnosis of OP (50.4% with fractures) and a serum tryptase assessment were reviewed. BM assessment was performed in a subset of hypertryptasemic patients; clinical, biochemical, and radiographic data were collected. Results Hypertryptasemia was detected in 33 patients. BM assessment (n = 16) was normal in 8 hypertryptasemic patients, while BM criteria for the diagnosis of SM were met in 3 patients, MC alterations were detected in 4 patients, and one patient presented a polycythemia vera. Serum tryptase levels were higher than 11.4 ng/ml in all patients with BM alterations. The best cut-off of tryptase level related to BM alterations was 17.9 ng/ml, with a sensibility and sensitivity of 75% (AUC = 0.797 and P = 0.015 by ROC analysis). All osteoporotic patients with hypertryptasemia experienced at least one vertebral fracture associated with a severe reduction of the lumbar bone mineral density. Conclusions The prevalence of MC-related disorders in severe OP was 3.0%, accounting for the 7.4% of the secondary causes of OP. MC-related disorders may be involved in bone fragility and assessment of serum tryptase is useful to detect MC-related disorders.
Highlights
Osteoporosis (OP) is a systemic skeletal disorder characterized by decreased bone mass and impairment of bone quality, which is associated with increased risk of fragility fractures
Diagnostic criteria have recently been updated on current WHO classification [5, 8, 9]; they include a biochemical finding, namely, serum tryptase levels higher than 20.0 ng/ml and histopathological, morphological, cytofluorimetric, and molecular criteria resulted from a bone marrow evaluation with bone marrow biopsy (BMB) and bone marrow aspirate (BMA)
Osteoporosis and fragility fractures are often clinical features of systemic diseases, whose diagnosis is mandatory in the management of osteoporosis
Summary
Osteoporosis (OP) is a systemic skeletal disorder characterized by decreased bone mass and impairment of bone quality, which is associated with increased risk of fragility fractures. Diagnostic workup for the secondary causes of OP requires extensive biochemical evaluation. In this context, the assessment of serum tryptase, a mastocyte cell-specific serine protease, could be considered in order to rule out systemic mastocytosis, a rare hematological disorder generally associated with hypertryptasemia [4]. Mastocytosis comprises a heterogeneous group of disorders characterized by expansion and accumulation of neoplastic mast cells (MCs) in one or more organ systems. In patients with systemic mastocytosis (SM), neoplastic MCs form focal and/or diffuse infiltrates in various internal organs, including the bone marrow (BM), spleen, liver, and gastrointestinal tract [5]. While the cutaneous mastocytosis spontaneously regresses in most cases, SM is a persistent disease, and it can evolve in more aggressive disorders, namely, aggressive SM or mast cell leukemia. Three minor criteria (persistent tryptase levels > 20:0 ng/ml, CD25 with or without CD2 aberrant expressions, abnormal mast cells morphology, and detection of the D816V KIT mutation) or one minor associated with the major criteria (i.e., multifocal dense mast cell aggregates) have to be met
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