Fibrosing mediastinitis

A 55 yr old female† presented to the department of Cardiology, MaxCure-Mediciti Hospitals, Hyderabad, India, in 18^th June 2018, with complains of early morning swelling of the face and neck for two years, which increased gradually to be present throughout the day. On examination, there was venous distension over the upper chest and neck with 'milking sign' being positive with flow directed upwards. Laboratory investigations were normal, except elevated serum creatinine (1.8 mg%). Computed tomography of the chest did not reveal any abnormality of the lungs. Invasive venography was done with limited contrast in view of elevated creatinine from right femoral, external jugular venous access, which demonstrated a blind pouch like obstruction of the right atrium and superior vena cava (SVC) junction (between two oblique lines) (Fig. 1A & B).

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Fig. 1

Invasive venography with limited contrast from right femoral using right coronary diagnostic catheter, direct sheath injection through external jugular venous access, demonstrated (A) a blind pouch (solid white arrow) like obstruction of the right atrium and (B) superior vena cava (SVC) junction (between two oblique lines), respectively.

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Initially, percutaneous angioplasty was done, but the lesion could not be crossed, as it was hard fibrotic lesion. Hence, palliative surgery was done to relieve her of symptoms using pericardial tube. The common jugular vein was connected to the right atrial appendage restoring the SVC flow. Postoperative chest X-ray revealed mild enlargement of the superior mediastinum with straightening of the right heart border (Fig. 2). The patient had relief from her symptoms after two weeks of surgery with the disappearance of veins over the chest.

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Fig. 2

Post-operative chest X-ray with midline sternotomy and artefacts by electrocardiogram cables showed straightening of the right border secondary to enlarged superior vena cava with interposition of graft and enlarged right atrium (solid white arrow). There was mild enlargement of superior mediastinum.

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Histopathology of the tissue obtained from the resected portion of SVC did not identify any infective cause, particularly chronic bacterial and fungal infections such as tuberculosis (culture and identification of Mycobacterium tuberculosis) or histoplasmosis (direct examination and/or culture of Histoplasma capsulatum), respectively. Histopathology of lymph nodes revealed perinodal fibrosis with prominence of plasma cells (suggestive of chronic inflammation), characteristics of sclerosing mediastinitis (Fig. 3). It is a clinical entity of unknown pathological process involving mediastinal structures, most commonly SVC. Chronic inflammation of idiopathic cause leads to excessive formation of collagen, which entraps the mediastinal structures and a variety of clinical presentations including SVC obstruction.

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Fig. 3

(A) Histopathology of lymph nodes (obtained from the post-operative surgical sample) (×100) stained with hematoxylin-eosin revealed perinodal fibrosis (solid black arrow) with prominence of plasma cells (dashed black arrows) which are characteristics of sclerosing mediastinitis. (B) At higher magnification (×400), the characteristic lamellar bands of dense fibrosis (inside the rectangle) similar to a keloid scar, with interspersed inflammation (inside the circle) were seen.

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