Chronic infection of the mediastinal tissues is characterized by proliferation of fibrous tissue in mediastinum with elements of granulomatous infection. It is benign, but can be invasive. Most commonly there is evidence of prior Histoplasma capsulatuminfection, especially in the USA, but it can also be triggered by tuberculosis, coccidiomycosis, aspergillus, blastomycosis, mucormycosis, and some other fungi, syphilis, and sarcoidosis. There is a great overlap in definition with sclerosing mediastinitis, which we here define as chronic infection of the mediastinum triggered by drugs like methysergide or by some idiopathic immune-mediated processes. Both forms are found under the same name of fibrosing mediastinitis. In histoplasmosis, granulomas in mediastinum are well formed and demarcated, usually with calcifications. Same type of granulomas occurs also in the lungs, liver, and spleen. In some patients, mediastinal granulomas can rupture...