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A7042 - Obstructive Pulmonary Hypertension Caused by Fibrosing Mediastinitis Successfully Treated with Riociguat
Author Block: B. V. Martinez1, D. R. Fraidenburg2; 1Medicine, University of Illinois Chicago, Chicago, IL, United States, 2Medicine, Division of Pulmonary, Critical Care, Sleep, and Allergy, University of Illinois at Chicago, Chicago, IL, United States.
Introduction: Fibrosing mediastinitis is a rare disease characterized by progressive fibrosis leading to compression of mediastinal structures and may affect the pulmonary arteries leading to pulmonary hypertension (PH). There is a strong association with prior granulomatous disease and immunotherapy has shown mixed results in preventing progressive fibrosis. Progressive disease with severe compressive symptoms may require palliative stenting or angioplasty of the pulmonary arteries, yet no medical therapies are shown to benefit patients with PH. We describe a case of fibrosing mediastinitis, initially misidentified as chronic thromboembolic disease, causing PH which had a favorable response to riociguat therapy.
Case Summary: A 62 year old woman with a past medical history of smoking, hypertension, diabetes mellitus, and prior pulmonary embolism presented to pulmonary clinic for evaluation of progressive dyspnea. Pulmonary function testing showed an isolated low DLCO. Ventilation and perfusion scan showed an unmatched perfusion defect in the apex of the right lung consistent with pulmonary embolism. CT of the chest showed mosaic lung attenuation bilaterally, dilated main pulmonary artery, and sequelae of old granulomatous disease, including calcified nodules and calcified lymphadenopathy. Estimated pulmonary artery systolic pressure by echocardiogram was 36 mmHg with mildly dilated right atrium and ventricle concerning for pulmonary hypertension. Right heart catheterization revealed a mean PAP of 45 mmHg, PAWP of 12 and PVR of 5.8 WU. Given the possibility of chronic thromboembolic PH, patient was started on riociguat and referred for pulmonary endarterectomy. Pulmonary angiogram showed tortuous, but patent vessels consistent with compressive fibrosing mediastinitis secondary to prior histoplasmosis infection. Anticoagulation was discontinued and the patient’s symptoms have improved while continuing riociguat. Echocardiogram showed improved pulmonary artery systolic pressure to 22 mmHg with normalization of RA and RV chamber dilation. Six minute walk distance remained stable with her best effort on treatment showing a 10 meter improvement from testing prior to treatment.
Discussion: Pulmonary hypertension caused by fibrosing mediastinitis is part of group 5 PH owing to multifactorial mechanisms. The compressive symptoms can lead to an obstructive PH and may be similar to that of chronic thromboembolic PH in which unaffected arterial vascular beds are subjected to additional turbulent blood flow and shearing forces that contribute to vascular remodeling. To our knowledge this is the first report of riociguat being used as a therapy for PH due to fibrosing mediastinitis and suspect that we have identified a plausible mechanism by which our patient improved on therapy.