CardioNerds Cofounder Dr. Amit Goyal join Dr. Usman Hasnie and Dr. Will Morgan from University of Alabama at Birmingham for a hike up Red Mountain. They discuss the following case: A 75-year-old woman with prior mitral valve ring annuloplasty presented with subacute, intermittent, self-limiting neurologic deficits. Brain MRI revealed multiple subacute embolic events consistent with cardioembolic phenomena. Transesophageal echochardiogram discovered a mobile mass on the mitral valve as the likely cause for cardioembolic stroke. She was taken for surgical repair of the mitral valve. Tissue biopsy confirmed that the mass was an IgG4-related pseudotumor. Expert commentary is provided by Dr. Neal Miller (Assistant Professor of Cardiology, University of Alabama at Birmingham). Audio editing by CardioNerds Academy Intern, student doctor Adriana Mares Check out this published case report here: IgG4-Related Disease Masquerading as Culture-Negative Endocarditis! CardioNerds Case Reports PageCardioNerds Episode PageCardioNerds AcademyCardionerds Healy Honor Roll CardioNerds Journal ClubSubscribe to The Heartbeat Newsletter!Check out CardioNerds SWAG!Become a CardioNerds Patron! Pearls - Cardioembolic Stroke due to an IgG4-related pseudotumor Surgical indications for endocarditis include severe heart failure, valvular dysfunction with severe hemodynamic compromise, prosthetic valve infection, invasion beyond the valve leaflets, recurrent systemic embolization, large mobile vegetations, or persistent sepsis (in infective endocarditis) despite adequate antibiotic therapy. IgG4 related disease is rare, and likely underrecognized due to the lack of reliable biomarkers. Biopsy and histologic confirmation are imperative to clinch the diagnosis. Cardiac manifestations of IgG4-related disease are rare but are often related to aortopathies. Valvular disease is extremely rare as a manifestation of the disease. Treatment of IgG4 related disease includes steroids as the first line treatment. IgG4 related disease requires a multi-disciplinary approach to both diagnose and treat. Show Notes - Cardioembolic Stroke due to an IgG4-related pseudotumor Notes were drafted by Dr. Hasnie and Dr. Morgan IgG4-related disease has a very diverse presentation including mimicry of infection, malignancy and other autoimmune conditions. It is a fibroinflammatory condition that results in deposition of IgG4 positive plasma cells. It has been described in multiple organ systems including the pancreas, kidneys, lungs and salivary glands.  Cardiac manifestations are extremely rare and valvular disease even more so. There are thirteen cases of IgG4 related valvular disease, and of these only two had mitral valve involvement such as this case. The most commonly reported cardiovascular manifestations are related to aortopathies.  This disease remains poorly understood at this point. There are no true biomarkers that can be used to risk stratify the diagnosis for clinicians. Biopsy is imperative to the diagnosis. Even serum IgG4 levels are normal in 30% of cases despite meeting histologic criteria on biopsy making the diagnosis incredibly difficult to make.  While guidelines have not been developed to guide treatment of IgG4-related disease, steroids are considered the first line treatment option for patients. Often times dosing is 2-4 weeks with a prolonged taper. When looking for glucocorticoid sparing agents, azathioprine, mycophenolate mofetil, and methotrexate are considered alternatives.  References - Cardioembolic Stroke due to an IgG4-related pseudotumor 1. Kamisawa T, Funata N, Hayashi Y, et al. A new clinicopathological entity of IgG4- related autoimmune disease. J Gastroenterol 2003;38:982-4.  2. Deshpande V, Zen Y, Chan JK, et al. Consensus statement on the pathology of IgG4-related disease. Mod Pathol. 2012;25(9):1181-1192. doi:10.1038/modpathol.2012.72  3. Dahlgren M,