Paravirus B19 infection imitating an acute exacerbation of systemic lupus erythematodes

History and admission findings: A 26-year-old woman, for 3 years known to h ave systemic lupus erythematodes (SLE), was admitted because of fever, musc le and joint pains as well as nausea and vomiting. Maintenance therapy of 5 0 mg azathioprine, three times daily, had been stopped by the patient sever al weeks earlier. Physical examination was unremarkable except for pale ski n and mucosae as well as pain on pressure over muscle groups of the upper a rms and thighs and paravertebrally. Diagnosis, treatment and course: Laboratory tests showed a pancytopenia wit h a decrease of the haemoglobin level of 3.0 gl dl. The differential diagno sis included an acute exacerbation of SLE, toxic damage to the bone-marrow by azathioprine or a viral infection involving the bone-marrow. Serological tests and the further course confirmed an acute paravirus B19 infection as the cause. Conclusion: Paravirus B19 infection should be included in the differential diagnosis when an acute exacerbation of SLE is suspected.