Serum tryptase monitoring in indolent systemic mastocytosis: association with disease features and patient outcome

This is an open-access article distributed under the terms of the Creative Commons Attribution License.-- et al.[Background]: Serum baseline tryptase (sBT) is a minor diagnostic criterion for systemic mastocytosis (SM) of undetermined prognostic impact. We monitored sBT levels in indolent SM (ISM) patients and investigated its utility for predicting disease behaviour and outcome. [Methods]: In total 74 adult ISM patients who were followed for ≥48 months and received no cytoreductive therapy were retrospectively studied. Patients were classified according to the pattern of evolution of sBT observed. [Results]: Overall 16/74 (22%) cases had decreasing sBT levels, 48 (65%) patients showed increasing sBT levels and 10 (13%) patients showed a fluctuating pattern. Patients with significantly increasing sBT (sBT slope ≥0.15) after 48 months of follow-up showed a slightly greater rate of development of diffuse bone sclerosis (13% vs. 2%) and hepatomegaly plus splenomegaly (16% vs. 5%), as well as a significantly greater frequency of multilineage vs. mast cells (MC)-restricted KIT mutation (p = 0.01) together with a greater frequency of cases with progression of ISM to smouldering and aggressive SM (p = 0.03), and a shorter progression-free survival (p = 0.03). [Conclusions]: Monitoring of sBT in ISM patients is closely associated with poor prognosis disease features as well as with disease progression, pointing out the need for a closer follow-up in ISM patients with progressively increasing sBT values.This work was supported by grants from the Fondo de Investigaciones Sanitarias (FIS) of the Ministerio de Ciencia e Innovación of Spain (RETICS RD06/0020/0035-FEDER and PS09/00032); Fundación Sociosanitaria de Castilla-La Mancha (FISCAM 2007/36, FISCAM 2010/008 and G-2010/C-002); Instituto de Salud Carlos III of the Ministerio de Economía y Competitividad of Spain (PI11/02399); Junta de Castilla y León (SAN/103/2011); Fundación Ramón Areces; Fundación Española de Mastocitosis (FEM 2010); Hospital Virgen de la Salud Biobank (BioB-HVS) supported by grant of RETICS RD09/0076/00074, (Toledo, Spain).Peer Reviewe