Background/Purpose:

The data on the Computed tomography (CT) changes of chest in Granulomatosis with polyangiitis (GPA) is available mostly from low tuberculosis prevalence countries. We planned to study the CT findings in confirmed GPA patients from a tuberculosis endemic area and compared these with published CT chest findings of post primary tuberculosis.

Methods:

Clinical and CT chest data from 40 patients with GPA was reviewed. The CT findings were classified as pulmonary parenchymal and pleural abnormalities. Parenchymal lesions were further defined as nodules (round opacity with diameter less than 3 cm), mass like consolidation (opacity greater than 3 cm in diameter with obscured underlying vessels) and ground glass opacities (not obscuring the underlying vessels). Lesions were also classified as angiocentric, centrilobular or subpleural based on their location. Cavitation, when present, was documented based on type, centric or eccentric, shape of inner wall margin as well as wall thickness. Architectural distortion of the lung, honeycombing, traction bronchiectasis, pleural or pericardial involvement and hilar or mediastinal lymphadenopathy, if present, were also recorded. We then compared our finding with those reported from two large European cohorts (One from the French vasculitis group and the other from the German group), one cohort each from USA, Mexico, Japan and Korea, and China. We then compared our findings with well described and widely cited CT findings in non HIV patients with Post Primary Pulmonary Tuberculosis.

Results: CT abnormalities were noted in both lungs in 34 and were unilateral in six (right sided in five) GPA patients. The findings were nodules (lesions less than 3 cm in diameter) in 15 (37.5%), masses (lesions more than 3cm) in 11 (27.5%) and ground glass opacities, consolidations and septal thickening in 16 (40%) each, pleural involvement in seven (17.5%), mediastinal lymphadenopathy and pericardial involvement in two(5%)  and parenchymal bands in one. Our patients had more consolidation and ground glass opacities, and much fewer parenchymal bands as compared to other series. While comparing the CT findings of GPA with Post primary tuberculosis, the consolidation in areas other than apical and posterior segment of upper lobe and superior segment of lower lobe, eccentric cavitation with smooth inner walls, widespread distribution of nodules with well-defined and clear margins along with the relative absence of mediastinal lymphadenopathy favoured GPA as compared to post primary tuberculosis.

Conclusion: Combination of CT chest findings can help in differentiating GPA from post primary tuberculosis in an endemic area.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/granulomatosis-with-polyangiitis-or-post-pulmonary-tuberculosis-can-ct-chest-help-in-differentiating-in-a-tuberculosis-endemic-area/