Autoimmune thyroiditis in the course of other autoimmune diseases such as systemic lupus erythematosus (SLE) is common because these disorders are attributed to the production of autoantibodies against various autoantigens. Beyond this association, autoimmune thyroiditis can occur before, during or after the development of SLE. In this report, we describe a female who presented with facial puffiness, lethargy and progressive abdominal distension. She was diagnosed with autoimmune thyroiditis followed by the diagnosis of SLE complicated by a massive ascites, a rare form of lupus peritonitis, which is sterile ascites that results from severe serositis. Her presentation was complex and posed a diagnostic challenge and dilemma to the physicians involved in her care.