ARRS 2022 Abstracts

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E1963. Chronic Granulomatous Inflammation and Pulmonary Fibrosis: Evolving Radiographic Features and Expanded Differential
Authors
  1. Rosita Shah; Hospital of University of Pennsylvania
Background
Unrecognized chronic granulomatous inflammatory disease in the thorax is associated with delayed diagnosis of often uncommon diseases, significant morbidity, and progression to pulmonary fibrosis. Substantial imaging differences between early and late disease reflect evolving histologic changes of active granulomatous inflammation, variable degrees of lymphocytic interstitial infiltration, and directed fibrotic destruction of pre-existing granulomas. This exhibit focuses on the pathophysiology, dynamic imaging features, and clinical entities associated with chronic granulomatous inflammation and eventual development of pulmonary fibrosis.

Educational Goals / Teaching Points
This exhibit aims to examine the pathophysiology of granulomatous inflammation including factors leading to irreversible fibrosis and the histologic differences of granuloma-associated fibrosis compared to fibrosis in usual interstitial pneumonitis; recognize early and late imaging findings of chronic granulomatous inflammation and patterns of resultant fibrosis; and discuss the imaging differential and unique clinical entities producing granuloma-associated fibrosis.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The radiographic diagnosis of granulomatous inflammation requires an understanding of the differences between early and late disease, especially the understanding that in cases of fibrosis, the expected nodularity associated with granuloma formation may no longer be present. Granuloma formation translates to the presence of nodules, which can be perilymphatic, centrilobular, peribronchial, or juxtapleural in distribution, and depending on the degree of histologic organization, range from indistinct ground glass opacities to distinct micro- and macronodules. Cases of severe inflammation may have consolidative features. The onset of fibrosis is often directed at the margins of granulomas such that they are eventually destroyed without an increase in extracellular matrix that occurs with usual interstitial pneumonitis. Peribronchial fibrosis with traction bronchiectasis is the most common distribution of fibrosis in granuloma-associated fibrosis.

Conclusion
The manifestations of early and late granulomatous inflammation vary significantly with nodular features, becoming less prominent in cases where fibrosis has developed. By recognizing these evolving imaging findings including peribronchial fibrosis, the radiologist may help select those cases where further evaluation is needed for diagnosis of granulomatous disease.