Evaluation of olfactory function as a potential biomarker in patients with Mastocytosis

Background: Mastocytosis is a clonal disease characterized by an accumulation of mastcells in various organs, such as skin, bones, lymph nodes, liver, spleen, peripheral and central nervous system, gastrointestinal and nose-pharyngeal tract. The serum tryptase, an enzyme produced almost exclusively by mastcells is considered as a biomarker. The serum concentration of tryptase can therefore be considered a quantitative sign and an indicator of activity of the organism's mast cells. The aim of the study was first to investigate odor threshold (OT), odor discrimination (OD) and odor identification (OI) in mastocytosis patients (MP) compared to age matches healthy controls (HC), then to correlate olfactory function with, serum tryptase. Method: Eighty subjects were enrolled in this study (40 patients with mastocytosis, 18 women and 22 men, mean age 47.9, SD 14.4 and 40 healthy controls, 16 women and 24 men 47.9, SD 14.7). OT, OD, OI and their sum TDI score were evaluated using the psychophysical Sniffin’ Sticks. The Montreal Cognitive Assessment (MoCA) was used to assess cognitive ability. One way between groups Multivariate analyses of variance (MANOVA) was carried out to assess the impact of olfactory function on the mastocytosis. Results: Among MP group, 10 (25%) reported normosmia, one patient functional anosmia and the remaining showed hyposmia. Our results indicated a statistical significant differences between the two groups (MP and HC) for the olfactory function and the MoCA [F(5,74)=504.7, p<0.0005, Wilks' Lambda =0.03, partial η2=0.972]. The analyses of each individual dependent variable, using Bonferroni adjusted alpha level showed significant differences between two groups for OT [F(1,78)=866.6, p<0.0005, partial η2=0.917], OD [F(1,78)=76.6, p<0.005, partial η2=0.495], for TDI [F(1,78)=379.6, p<0.005, partial η2=0.830] and for MoCA [F(1,78)=146.3, p<0.005, partial η2=0.652]. Instead, no statistical significant difference was found for OI [F(1,78)=0.62, p>0.05, partial η2=0.008]. Significant negative correlation was observed between the TDI versus serum tryptase (r=-0.398, p<0.05). Conclusion: Our data suggest that olfactory dysfunction could represent a potential biomarker to be more extensively evaluated for an early diagnosis of Mastocytosis.