Contributed by Gerard Joey Oakley, MD
The patient is a 10 year old female, active in dance classes. She is referred to rheumatology at UPMC following a week-long bout of malaise accompanied in the last several days by a pruritic lacy rash on her trunks and limbs (Figure 1). An anti-nuclear antibody (ANA) assay obtained by the outside physician at an outside laboratory was positive to a titer of 1:1,280.
Figure 1: "Lacy" pruritic rash. Photograph from DermNet.com, maintained by Alan N. Binnick and Thomas P. Habif, Dartmouth School of Medicine, http://www.lib.uiowa.edu/hardin/md/dermnet/fifthdisease6.html
On presentation at the rheumatology clinic, the pruritic lacy rash is again evident on the trunks and limbs. No photosensitivity or any appearance of a malar-type rash is appreciated. The patient is afebrile and reports no significant constitutional symptoms. On physical examination, the oropharynx is normal and no splenomegaly is appreciated. She provides additional history of exposure to parvovirus and Epstein Barr virus in dance class prior to the onset of her recent illness. There is no family history of rheumatologic disease.
Believing this condition to represent infectious disease versus early rheumatologic disorder (given the high-titer positive ANA), additional laboratory studies were obtained. C-reactive protein, complement protein C3, and immunoglobulin subtype quantities were within normal limits. Complement protein C4 was below detectable limits. Specific antibody testing for anti-double stranded DNA, anti-centromere, rheumatoid factor, Epstein Barr virus nuclear antigen IgG, Epstein Barr virus capsid antigen IgG and IgM were all negative. Anti-parvovirus IgG is negative; however, anti-parvovirus IgM is positive at 6.6 mg/dL. Repeat ANA is positive to a titer of 1:160, with a speckled pattern observed. Her complete blood count and differential were unremarkable.