Low risk of contrast media-induced hypersensitivity reactions in all subtypes of systemic mastocytosis.

Background Patients with SM are at increased risk of hypersensitivity reactions. Although hymenoptera venoms are the predominant triggers, cases of CMIHR have also been reported and prophylactic premedication is often performed. However, data from larger series are limited and differences between indolent and advanced systemic mastocytosis have not yet been investigated. Objective To determine the incidence and severity of CMIHR in all subtypes of SM. Methods: We analyzed 162 adult patients with SM (ISM, n=65; advSM, n=97). Firstly, the cumulative incidence of CMIHR was retrospectively assessed in the patient's history. Secondly, at our institution, patients underwent 332 CM-enhanced imagings including 80 CT scans with iodine-based contrast agent and 252 MRI with gadoliniumbased contrast agent and tolerance was assessed. Results Previous CMIHRs to CT (vomiting, n=1, erythema, n=1, cardiovascular shock, n=1) and MRI (dyspnea, n=1, cardiovascular shock, n=1) had been reported by 4/162 (2.5%) patients (ISM, n=3; advSM, n=1). In contrast, during or after 332 CM-enhanced CT/MRI examinations at our institution, no CMIHRs were reported. Premedication was solely given to 3 patients prior to CT scans, including one with previous CMIHR, who tolerated the imaging well. Conclusion We conclude that i) there is a significant discrepancy between perception and prevalence of hypersensitivity reactions to CM in SM, ii) reactions are scarce in ISM and even rarer in advSM, iii) in SM patients without previous history of CM hypersensitivity, prophylactic premedication prior to CM enhanced-CT/MRI is dispensable.