Paraneoplastic symptoms, caused by a malignancy, but not directly related to invasion
by the tumor or its metastases are the result of a wide variety of tumor-derived biologic
mediators like hormones, peptides, antibodies, cytotoxic lymphocytes, autocrine and
paracrine mediators. Recognition of paraneoplastic syndromes is important, as it may
lead to an early diagnosis of cancer. There is some evidence that systemic inflammatory
diseases, such as rheumatoid arthritis (RA), lupus, scleroderma or dermatomyositis
may increase the risk for the development of malignancies, predominantly lymphoproliferative
disorders. However, reports are somewhat controversial. Immunosuppressive and cytotoxic
drugs used in antirheumatic therapy, such as methotrexate, cyclophosphamide, azathioprine
or anti-TNF biologicals may also lead to the development of such tumors. Tumor-associated
antigens may be produced by inflammatory cells and their production may be increased
in RA and other autoimmune diseases.