The Pulmonary Manifestation of Mastocytosis: Experiences of the National Reference Centre of Excellence

<b>Background:</b> Patients with mastocytosis may present with exacerbated respiratory symptoms and lung diseases resulting from mast cell mediator release. However, their prevalence and severity level remain under debate. The study aims to analyze the prevalence of respiratory symptoms and the usefulness of lung function tests like spirometry, diffusing capacity of the lung for carbon monoxide (DLCO), and high-resolution computed tomography (HRCT) of the chest in mastocytosis patients presenting with dyspnea, cough, and exercise intolerance. <b>Methods:</b> We included 104 patients with mastocytosis and 71 healthy controls. Data collection encompassed patient interview, clinical examination, spirometry, DLCO, and chest HRCT. Diagnosis of mastocytosis included bone marrow biopsies and serum tryptase measurements. <b>Results:</b> Compared to controls, patients with mastocytosis exhibited significantly lower values in FEV1/VC ratio, absolute DLCO/VA, predicted DLCO/VA, absolute DLCOcSB, and predicted DLCOcSB (<i>p</i> < 0.001). Commonly reported respiratory symptoms included dyspnea (36.5%), chest tightness (22.1%), and wheezing (9.6%). Airway obstruction was identified in 7.7% of patients; however, it appeared to be independent of the mastocytosis subtype. A decreased DLCO/VA ratio was observed in 4.8% of patients, but HRCT did not reveal any evidence of underlying lung disease. <b>Conclusions:</b> Mastocytosis appears to be a risk factor for the occurrence and exacerbation of respiratory symptoms. However, airway obstruction and impairment of the alveolar-capillary membrane seem to occur independently of the clinical subtype of mastocytosis. Additionally, the causal relationship between pulmonary involvement, mast cell infiltration of the alveolar-capillary membrane, and the systemic circulation of mast cell mediators remains unclear and requires further research.