Background: Mastocytosis is characterized by the accumulation of abnormal mast cells in various organs. Data on the prevalence of mastocytosis are heterogeneous, with the condition’s prevalence estimated to be between 9.6 and 23.9 per 100,000 inhabitants. Patients may present signs and symptoms that can severely impact quality of life (QoL), but reported data are scarce. Thus, we performed a nationwide study to estimate the prevalence and to assess the management and burden of adults with mastocytosis in France according to physician assessments. Methods: We developed an online survey comprising 25 questions investigating various aspects of mastocytosis and asked 6,239 physicians to respond. Data concerning physician characteristics and the number of patients followed were used to estimate overall prevalence. To assess patients’ QoL, we focused on the presence of signs and symptoms and the patients’ burden specifically in those with either indolent systemic mastocytosis (ISM) or mastocytosis in the skin (MIS). Results: Between July 11, 2023, and September 1, 2023, 1,169 physicians (18.7%) completed the survey. These physicians managed 4,121 mastocytosis patients, corresponding to an estimated prevalence of mastocytosis of 8.5 per 100,000 in France. In the ISM/MIS population (representing 76% of mastocytosis patients), 53% presented moderate to severe symptoms (mainly skin, digestive and general symptoms). Overall, physicians indicated that there was substantial burden associated with these symptoms in almost all fields of QoL analyzed. Conclusions: Our results provide further evidence of the burden associated with mastocytosis and highlight the need to improve QoL in these patients.

Hereditary angioedema (HAE) is a rare, life-threatening genetic disorder characterized by acute, recurrent and unpredictable episodes of cutaneous or submucosal angioedema, mediated by bradykinin, due to C1 inhibitor (C1INH) abnormalities in the vast majority of cases. The epidemiology of the disease is poorly documented in children. Clinical manifestations usually appear during childhood or early adolescence. Classical signs, preceded by prodromal symptoms in 50 % of cases, include transient, localized, non-pitting, non-pruritic swelling of deep dermal/subcutaneous or mucosal/submucosal tissues, leading to oedema of the extremities, face, lips, tongue, trunk and genitals, recurring gastrointestinal symptoms and laryngeal edema possibly causing asphyxiation and death. Diagnosis is often delayed due to low awareness in the medical community, and particularly challenging in case of isolated abdominal crises or atypical presentation and in neonates or infants. It relies on biological tests (measurement of serum/plasma levels of C1INH function, C1INH protein, and C4), genetic testing in selected cases, and imaging for differential diagnosis of acute abdominal crises. Main differential diagnosis for peripheral oedema is mast cell-mediated oedema that accounts for 95 % of angioedema in clinical practice. Quality of life can be significantly impaired. Disease management includes treatment of attacks, short-term and long-term prophylaxis, psychological support, avoidance of triggers, patients’ and parents’ education and coordination of all stakeholders, ideally within a specialized healthcare network. New plasma kallikrein inhibitors, namely lanadelumab (subcutaneous route) and berotralstat (oral route) have facilitated long-term prophylaxis thanks to improved usability.

A document by Aude Belbezier. Click on the document to view its contents.