Mitrovic-Jovanovic, Milica (56257450700)Milica (56257450700)Mitrovic-JovanovicSkrobic, Ognjan (16234762800)Ognjan (16234762800)SkrobicOdalovic, Strahinja (57218390032)Strahinja (57218390032)OdalovicDjikic Rom, Aleksandra (56182303300)Aleksandra (56182303300)Djikic RomPlavsic, Aleksandra (24169362300)Aleksandra (24169362300)PlavsicJankovic, Aleksandra (57205752179)Aleksandra (57205752179)JankovicKostadinovic, Milena (57205204516)Milena (57205204516)KostadinovicIvanovic, Nenad (55375283100)Nenad (55375283100)IvanovicSimic, Aleksandar (7003795237)Aleksandar (7003795237)SimicDjuric-Stefanovic, Aleksandra (16021199600)Aleksandra (16021199600)Djuric-StefanovicKovac, Jelena Djokic (52563972900)Jelena Djokic (52563972900)Kovac2025-07-022025-07-022023https://doi.org/10.1177/03000605231213212https://www.scopus.com/inward/record.uri?eid=2-s2.0-85178333307&doi=10.1177%2f03000605231213212&partnerID=40&md5=e0b71a91121634e7ea90ef7e1cd9f0a5https://remedy.med.bg.ac.rs/handle/123456789/11689Idiopathic mediastinal fibrosis, also called sclerosing or fibrosing mediastinitis, is a very rare and aggressive fibroinflammatory process characterized by fibrous tissue proliferation in the mediastinal region. Herein, we present a rare case of idiopathic mediastinal fibrosis presenting with esophageal obstruction, most likely associated with immunoglobulin G (IgG4)-related disease, affecting the posterior mediastinum with intrapulmonary infiltration. Computed tomography revealed a narrowed lumen and thickened wall of the distal esophagus surrounded by a necrotic mass with infiltration into the nearby structures, suggesting a locally advanced malignant process. Positron emission tomography revealed intense accumulation of 18F-fluorodeoxyglucose, indicating an active inflammatory component, which complicates further differential diagnosis of mediastinal masses. Thoracoscopic biopsy and immunohistochemical analysis confirmed a fibroinflammatory process with perivascular lymphoid cell infiltration that was cluster of differentiation (CD)3 (++) and CD20 (++), with massive numbers of IgG4-immunoreactive plasma cells. Although a benign condition, sclerosing mediastinitis is a close mimicker of esophageal carcinoma, which cannot be differentiated by computed tomography or positron emission tomography and must be considered in a differential diagnosis. © The Author(s) 2023.case reportcomputed tomographydifferential diagnosisesophageal carcinomaIdiopathic mediastinal fibrosisIgG4-related diseasepositron emission tomography