False-positive dengue IgM test result in a patient with systemic lupus erythematosus: a case report

Dengue virus infection most commonly has mild-to-moderate nonspecific clinical presentations that overlap with other diseases. Dengue-specific tests are commonly used for those patients with acute febrile illness in dengue-endemic areas. There is one study in vitro that showed a false-positive dengue-immunoglobulin M (dengue IgM) test for blood from a patient with systemic lupus erythematosus (SLE). Here, we demonstrated a false-positive dengue IgM test in a patient with SLE. The patient had fever, cytopenia, and a skin rash, but her clinical variables more closely matched with the criteria for SLE than the dengue infection. Vasculitis-like-lesions supported prednisolone administration and her clinical symptoms improved. This case highlights that some patients with SLE can be misdiagnosed as having a viral infection. These two diseases have similar clinical findings, such as acute febrile illness, but they are different in terms of their treatments and disease prognosis.