Is This Papular Eruption Secondary Syphilis?

 A 31-year-old man seeks evaluation of a pruritic papular eruption on his trunk of 2 weeks’ duration. He denies fever, malaise, and medication use.

Your first step is to...

A.  Perform a skin biopsy.
B.  Obtain a complete blood cell count and chemistry panel.
C.  Perform a VDRL test.
D.  Obtain a chest radiograph.
E.  Obtain an antinuclear antibody titer.

(Answer on next page.)

Answer: C. Perform a VDRL test.

This is a typical presentation of pityriasis rosea, which usually manifests as oval-shaped, salmon-colored macules or erythematous papules. Since secondary syphilis can mimic pityriasis rosea, a VDRL test, C,  can be useful; the other tests are of limited value.