Pulmonary venous outflow obstruction secondary to fibrosing mediastinitis triggered by histoplasmosis: A case report

We report a case of long-standing fibrosing mediastinitis (FM) in a 63-year-old female with prior Histoplasma capsulatum infection, complicated by complete obstruction of the left pulmonary venous outflow and marked hypoperfusion of the left lung. Remarkably, the patient remained largely asymptomatic despite extensive anatomic compromise, offering important insights for imaging-based evaluation and management. A ventilation-perfusion (V/Q) scan demonstrated left lung hypoperfusion, and computerized tomography revealed calcified nodules suggestive of fibrosis. Digital subtraction pulmonary angiography confirmed elevated pressures across the main, right, and left pulmonary arteries and absence of outflow through the left superior and inferior pulmonary veins with cavernous transformation. While recanalization was considered, intervention was deferred given severe obstruction and minimal symptoms. This case underscores the role of multimodality imaging in diagnosing venous outflow obstruction and highlights compensatory vascular remodeling in chronic FM. The educational value lies in balancing intervention versus observation in asymptomatic patients with significant structural disease.