Nodular distribution pattern on chest computed tomography (CT) in patients diagnosed with nontuberculous mycobacteria (NTM) infections

Background This study evaluated the prevalence ofspreading pathways in nontuberculous mycobacteria(NTM) pulmonary infections according to nodulardistribution patterns seen on chest computed tomog-raphy (CT). Methods This study included 63 patients diagnosedwith NTM lung infections who underwent CT at ourinstitution. A retrospective analysis of CT images fo-cused on the presence and distribution of nodules, presence of intrathoracic lymphadenopathy and thepredominant side of infection in the lungs. The find-ings were classified into five groups ; centrilobular(bronchogenic spread), perilymphatic (lymphangiticspread), random (hematogenous spread), combinedpattern and no nodules present. The groups werethen compared according to other CT findings. Results Among 51 (81%) patients identified with anodular pattern on chest CT, 25 (39.8%) presentedwith centrilobular, 7 (11.1%) with perilymphatic, 6(9.5%) with random and 13 (20.6%) with combinednodular patterns but located in different areas of thelungs. The right side of the lungs was predominantin 38 cases (60.3%). Intrathoracic lymphadenopa-thy was evident in 20 patients (31.7%). Significantdifferences in distributions of nodular patterns wereseen in patients infected withMycoplasma aviumcomplex(MAC) associated with centrilobular pat-tern (p= 0.0019) andM. fortuitumassociated withrandom pattern (p= 0.0004). Some of the findingswere related to perilymphatic nodules between otherisolated species of NTM (p= 0.0379). Conclusion The results of this study showed a highproportion of perilymphatic nodules and right-sidedpredominance in the upper lobe, which, combinedwith intrathoracic lymphadenopathy is highly sugges-tive of the lymphangitic spread of lung NTM infec-tions.