Polyarthritis presented in a patient with untreated chronic hepatitis B infection.

Hepatitis B virus (HBV) infection can cause arthritis, but it is rarely reported. In the current report, we present a case of chronic polyarthritis in a patient with untreated HBV infection. A 63-year-old woman suffering from polyarthritis in her fingers visited our institution. She had experienced exacerbations and remissions of polyarthritis for more than 20 years. She had been diagnosed with rheumatoid arthritis and had been treated with conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) and non-steroidal anti-inflammatory drugs by her primary care doctor, but the csDMARDs were discontinued at the request of the patient 10 years before the first visit to our hospital. The blood test showed negative for rheumatoid factor and anti-cyclic citrullinated peptides antibody, but positive for hepatitis B surface antigen (HBsAg). HBsAg and HBV-DNA were increased to 312.6 (IU/mL) and 4.6 (Log copies/mL), respectively. Based in the results of abdominal CT and echography, she was diagnosed with liver cirrhosis. Treatment for HBV infection was begun with oral tenofovir at 25mg/day. The polyarthritis in her fingers gradually disappeared and has not relapsed for 6 months after the initiation of treatment for HBV infection. When polyarthritis is diagnosed, the possibility that chronic HBV infection can be one of the causes of polyarthritis should be considered.