Thymoma as a Potential Risk Factor for Nontuberculous Mycobacterial Pulmonary Disease

Nontuberculous mycobacteria (NTM) are environmental microorganisms that can cause chronic progressive lung disease.Although NTM are widespread in the environment, particularly in the water and soil, only a small proportion of people who are exposed eventually demonstrate disease. 1 Established risk factors for nontuberculous mycobacterial pulmonary disease (NTM-PD) include structural lung diseases, principally bronchiectasis (sometimes caused by cystic fibrosis or primary ciliary dyskinesia) and COPD immunodeficiency (possibly from HIV or medications), and immune dysregulation from autoimmunity. 2 In many patients, often those who are female and slim, NTM-PD can present without any antecedent lung conditions or overt immunologic abnormalities.For these patients, the questions of why and how are raised often, highlighting the gaps in our understanding of NTM-PD risk factors and pathogenesis.Herein, we describe a series of patients with bronchiectasis and NTM-PD in the context of pathologically confirmed thymoma.We outline the characteristics and outcomes of these patients and present theories as to potential explanations behind thymoma as a risk factor for NTM-PD. MethodsThis case series was conducted at the 1,500-bed, multicampus University Health Network, Toronto, Canada.We searched electronic medical records for patients who (1) had an admitting diagnosis of thymoma and (2) positive mycobacterial culture