D3.419 - Prevalence of physical urticaria hives in patients with systemic mastocytosis and their relation to disease course – preliminary data

Mastocytosis is a rare bone marrow disease that results from abnormal proliferation and activation of mast cells. Patients with indolent type suffer mostly from mast cell degranulation symptoms with significant skin manifestations including itching, urticaria, edema, flushing. Many patients report itching generalized hives that are triggered by physical stimuli such as cold, heat, pressure though their prevalence was not yet thoroughly studied to date. Similarly, in hereditary alpha tryptasemia increased physical vibration urticaria is observed alongside with other mast cell activation symptoms. The aim of our study was to investigate prevalence of physical urticaria and its relation to disease markers such as tryptase

A total of 31 patients with systemic mastocytosis were enrolled randomly. In this group 21 patients also had skin involvement (urticaria pigmentosa). All patients were asked about prevalence of physical urticaria. In all patients we performed physical urticaria tests on forearm: ice cube, cold/heat applying device (4-44 deg Celsius), vortex vibration, 5kg pressure on sling. Historical serum tryptase was also noted. All tests were also performed on 13 healthy controls with negative interview towards urticaria. Chi square test was used in comparison of dichotomous outcomes and regression analysis was used for continuous variables.

Patients reported positive history of urticaria: cold (9/31 positive), pressure (8/31), heat (14/31) and vibration (0/31). All ice cube, cold/heat and pressure tests were negative in both patients and controls. Vibration vortex test was positive in 10(32%) patients and in 1(8%) healthy control (chi square p value=0.08). No difference was observed between patients with urticaria pigmentosa and without skin manifestation (chi square p=0.21) Regression analysis of tryptase and wheal diameter triggered by vibration revealed borderline significant relation with serum tryptase (p=0.047 coef=1.02 CI:0.01-2.04).

Most common trigger in physical urticaria tests in mastocytosis is vibration. Higher serum tryptase might contribute to greater skin response on vibration test. These observations suggest similarity of hereditary alpha tryptasemia and systemic mastocytosis. The study will continue recruitment.