A Neglected Rare Disorder: Igg4 Related Disease

Abstract IgG4–related disease (IgG4–RD) is an autoimmune disorder characterized by infiltration of plasma cells with IgG4. Almost any organ could be affected. Common presentations include lung manifestation, autoimmune pancreatitis, retroperitoneal fibrosis and tubulointerstitial nephritis. Cardiovascular involvement is less frequent. Corticosteroids are first line therapy, with or without anti–rheumatic drugs. Long–term prognosis of IgG4–RLD remains unknown. We present the case of a 65–years old woman, with a previuos diagnosis of IgG4–RD with mediastinal involvement. In the meantime she was recovered for pyelonephritis with high fever and positive blood coltures (S. hominis). We were called to perform a transthoracic echocardiogram to rule out infective endocarditis. The exam showed normal size of cardiac chambers, normal biventricular systolic function, absence of relevant valvular disease. In apical view we noticed a hyperechogenic ovalar imagine in the right atrium, not visible in all the projections. A first differential diagnosis included a mass with site of implantation at the top of the right atrium or something external but contiguous to heart structures. To clear this doubt the patient performed a thoracic CT with stunning results. The CT highlighted parietal encasement of chardiac structures and, particularly, of the superior vena cava at the confluence in right atrium, explaining the image we saw with transthoracic echo. The exam also showed encasement of ascending aorta, aortic arch and descending aorta with maximum thickness of 18 mm. CT also reported encasement of right pulmonary arthery. The CT highlighted a progression of the disease with indication to more aggressive therapy. In fact IgG4–RD of the cardiovascular system results in serious complications that need to be recognized and treated. Aortic involvement in IgG4–RD is extremely rare and tipically affects the infrarenal abdominal aorta. Cardiovascular IgG4–RD could also lead to aortitis, medium–vessel arteritis, pulmonary vascular disease, phlebitis, valvulopathy, pericarditis and myocardial disease. These forms of Igg4–RD are often underdiagnosed as clinical presentations is similar to cardiovascular disease due to more common aetiologies. Regarding our case the patient began methotrexate based on the results of the CT. This was a really interesting case for our working group to deepen this little–known disease. “The eyes see only what the mind is prepared to comprehend”.