Paraneoplastic syndromes are a group of rare disorders caused by a mal ignancy, but not directly related to invasion by the tumor or its metastases. It is known that tumor cells express antigens which can induce the formation of specific autoantibodies. Awareness of the associations between rheumatic manifestations, auto-immunity and malignancy will aid the clinician in the accurate diagnosis of underlying pathology, more effective treatment of both the symptoms and underlying disease.
Objective. To assess diagnostic value of autoantibodies in paraneoplastic rheumatic syndromes.
Patients and methods. Ninety-three patients (48 with solid tumor and paraneoplastic rheumatic syndromes and 45 with solid tumor only) were evaluated and examined for the presence of autoantibodies. The white blood cell count (WBC), erythrocyte sedimentation rate (ESR) and C-reac-tive protein (CRP) were recorded from the medical history. Rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibody (anti-CCP) test was performed with the help of the enzyme-linked immunosorbent assay (ELISA). Antinuclear antii bodies (ANA) were tested by indirect immunofluorescence on Hep-2 cells. Immunoblotting techniques were used to detect autoantibodies to extractable nuclear antigens (ENA) and anti-neuronal antibodies (ANNA).
Results. The group of patients with arthritis and the the group of patients with Raynaud's syndrome were found to prevail among other clinical presentations of paraneoplastic rheumatic syndromes. RF was detected in 31% of pai tients with paraneoplastic rheumatic syndrome and in 20% of control group. 25% of patients with rheumatic syndrome and 25% control group patients had ANA. The speckl ed pattern was observed in most ANA-positive patients. ENA was present in 27.1% of paraneoi plastic patients and 10% of control group patients. ANNA were rare in mal ignan-cies with paraneoplastic rheumatic symptoms and solid tumors (8.3% and 6.7% respectively). Significant difference wasn't observed comparing frequency of detecting autoantibodies in the group of patients with paraneoplastic rheumatic syndromes and control group with solid tumors. No significant difference were observed comparing frequency of detecting autoantibodies in the group of patients with tumors of difterent localiza i tion, except for patients with lung cancer were most frequent RF positive (45%) compared with patients with breast cancer (5.9%) or tumors of the genital system (29%) (x2=7.017; p=0.030).
We detected that leukocytosis and high levels of ESR are associated with tumor locali zation and are highest for patients with lung cancer.
Conclusion. Rheumatoid factor, antinuclear autoantibodies, autoanti-bodies to extractable nuclear antigens and anti-neuronal antibodies were found to be simít arly frequent in the paraneo i plastic and the control groups. The immunology profile is of limited use in paraneoplastic rheumatic syndomes. The determination of inflammatory parameters can be helpful to identify the underlying malignancy.
Keywords: paraneoplastic syndromes, autoantibodies, tumors.
