Abstract Introduction Fibrosing mediastinitis (FM) is a rare, benign yet locally aggressive fibroinflammatory disorder characterized by excessive proliferation of dense fibrous tissue in the mediastinum, which can compress vital mediastinal structures, including the superior vena cava (SVC), pulmonary arteries, and bronchi. It is more commonly associated with a history of chronic pulmonary histoplasmosis, granulomatous diseases, or autoimmune processes, but may also be idiopathic.Detecting pulmonary fibrosis on low-dose computed tomography (LDCT) is exceptionally uncommon as LDCT protocols prioritize parenchymal evaluation with limited mediastinal soft-tissue resolution. In large screening cohorts, interstitial lung abnormalities are detected in approximately 9-10% of participants, but the subset with fibrotic changes accounts for only 2% of screened individuals. Case Presentation A 52-year-old male with a 30-pack-year smoking history and occupational exposure as a fire service engineer presented after routine LDCT lung cancer screening. He was otherwise asymptomatic except for mild sleep disturbance under evaluation for obstructive sleep apnea. The LDCT demonstrated multiple small, noncalcified pulmonary nodules (3 mm in the right upper lobe and 2 mm in the left upper lobe) and mild centrilobular emphysema. It also showed partially calcified right paratracheal and subcarinal lymph nodes, along with abnormal calcification along the wall of the SVC and collateral venous varicosities along the left chest wall, suggestive of chronic SVC obstruction secondary to fibrosing mediastinitis. No pleural effusion or parenchymal mass was identified. The patient denied prior fungal infections or systemic symptoms. Laboratory workup, including Histoplasma, Blastomyces, Aspergillus, and Coccidioides serologies, was ordered. Echocardiography to evaluate for pulmonary hypertension, and CT venography of the chest to assess the extent of vascular obstruction, was recommended. Discussion This case discusses the incidental recognition of fibrosing mediastinitis on LDCT performed for lung cancer screening. FM is typically identified on contrast-enhanced CT or MRI due to the need for detailed soft-tissue characterization, while LDCT provides limited mediastinal resolution. The incidental identification of SVC calcification and chest wall collateral circulation in this case highlights the expanding diagnostic potential of LDCT beyond pulmonary nodule detection. Few reports describe FM discovered incidentally on LDCT. Early recognition of radiologic clues like calcified mediastinal nodes, vascular wall calcification, and venous collaterals can help initiate early work-up before SVC obstruction or pulmonary hypertension becomes symptomatic. Therefore, we should maintain a broad differential diagnosis when evaluating LDCT findings, as clinically significant nonmalignant thoracic conditions may be detected incidentally. This abstract is funded by: NONE
Khan et al. (Fri,) studied this question.