Many different diseases have overlapping clinical symptoms. A major challenge in daily clinical practice is to differentiate between diseases associated with systemic inflammation, such as neoplasia, infection and autoimmune disease. We report on a 46-year-old Caucasian male with a 3-month history of rheumatoid arthritis presenting with dramatic weight loss and dysphagia. Computer tomography revealed multiple lesions in the liver and the spleen, strongly suggesting malignant disease of unknown origin. Surprisingly, on biopsy, the liver lesions drained pus. Workup revealed that the abscesses resulted from gastric perforation, which was the consequence of NSAR therapy for rheumatoid arthritis. Antibiotic therapy was initiated, abscesses diminished and dysfunctional deglutition improved. This unique case demonstrates in a dramatic way the difficulties in daily clinical practice to differentiate between paraneoplasia, infection and autoimmune disease and the potentially life-threatening consequences of their therapy.