Isolated autoimmune response: definition, analysis of the prevalence in an outpatient rheumatology clinic, relationship to pre-clinical autoimmune disease and infections by hepatotropic viruses.

Objective To define the clinical significance of non-organ specific autoantibody positivity in patients in whom routine clinical and laboratory examinations did not detect any disease that might have caused the serological finding. Methods Out of 1,120 patients consecutively admitted to an outpatient rheumatology clinic, 28 were referred for the evaluation of an autoantibody positivity unrelated to the clinical status. These patients and 28 sex- and age-matched controls underwent a specific work-up with the aim of detecting any underlying infection or autoimmune disease. Results Eight of the 28 patients (28.5%) were found to be affected by a previously undetected disease: 3 chronic hepatitis C, 3 Sjogren's syndrome, and 2 autoimmune thyroiditis. The remaining 20 did not show any autoimmune or hepatic disease, although 4 of them showed active infection by HBV (n = 1) or HGV (n = 3) and 15 had had a previous infection by hepatotropic viruses (HBV CMV or EBV). After a follow-up lasting 6-54 months, none of the last 20 patients developed any autoimmune or chronic hepatic disease. Conclusions A diagnostic work-up is necessary in patients presenting with unexpected autoantibody positivity in order to detect an underlying pre-clinical autoimmune disease and/or unexpected hepatic infection. Patients in whom such a workup fails to point out any condition should be further followed in order to make an early diagnosis of autoimmune disease.