Autoimmune diseases presenting with IgG4 related lesions at atypical sites - a tale of two cases with literature review

Introduction: IgG4RD overlapping with clinically overt autoimmune diseases (Rheumatoid arthritis ( RA) or anti-phospholipid syndrome (APS) is rarely reported in the literature. Here we report a tale of two cases with known autoimmune diseases – RA and primary APS presented with IgG4-related lesions involving unusual sites – oesophagus and right atrium of the heart respectively Case – The first case was a known RA presented with dysphagia, imaging suggestive of encasing mass in oesophagus causing stricture , biopsy was suggestive of IgG4RD. The second patient was a known case of primary APS presented with breathlessness, imaging revealed right atrial mass with histopathology was suggestive of IgG4RD . Both patients had significant improvement after starting steroid. Discussion – A few cases of known RA presenting with IgG4 mass is reported in literature though RA patients are frequently found to have increased number of IgG4 in their sera. Primary APS with IgG4 lesion is extremely uncommon. Though a several case reports or series are published regarding oesophageal and cardiac IgG4 related lesions, such lesions in the background of known autoimmunity is first described by us . Conclusion – This is the first case series of two cases with IgG4 related lesions in atypical site in known autoimmune diseases .