[Parvovirus B19-induced arthritis/arthropathy--an important differential diagnosis of chronic polyarthritis]

The differential diagnosis of rheumatoid arthritis (RA) and parvovirus-B19-induced arthritis/arthropathy (PBA) can be difficult, but is of importance because of the different therapeutic implications. The purpose is to describe characteristic features serving to differentiate between chronic PBA and RA, based on 6 personal cases and the literature.

6 patients presenting with acute (3 cases) or chronic PBA (3 cases) over the last 5 years are described.

The demonstration of anti-parvovirus-B19-immunoglobulins (Ig)M in addition to anti-parvovirus-B19-IgG is the most important diagnostic finding. Measurement of IgM must be done within the first months after onset, as it disappears later on. Furthermore, history of disease (exposure, prodromi and acute onset of arthritis), clinical examination (rash) and further investigations (normal ESR and CRP, typical hematologic findings, examination of synovial tissue and fluid without inflammatory changes, demonstration of the genome of parvovirus B19 by polymerase chain reaction, no erosions on radiographs) support the diagnosis of PBA. 2 of the 3 patients with chronic PBA fulfilled the criteria for classification of RA. Therapeutic approaches in PBA are discussed. In contrast to the favourable effect in RA, immunosuppressive agents may prolong persistence of virus and disease in PBA.