A 58-year-old female patient was referred to our department with a 1-year history of markedly elevated inflammatory markers and progressive anemia. Her chief complaint was a progressive weight loss of 14 kg within 10 months accompanied by decreased appetite, as well as recurrent oral aphthous stomatitis, dyspnea on exertion, and occasionally mild fevers up to 38.3°C. She denied any diarrhea or current joint symptoms. Thirteen years ago, she was diagnosed with seronegative rheumatoid arthritis. Her past medical history was also significant for an episode of polyserositis.