The great imitator revisited: the spectrum of atypical cutaneous manifestations of secondary syphilis

Syphilis is a well-known sexually transmitted infection infamous for its protean cutaneous manifestations. Over the last decade, the rate of infection in the USA has risen, particularly among human immunodeficiency virus (HIV)-infected individuals and certain ethnic groups. Although the primary chancre developing at the site of inoculation usually has typical and well-characterized features, cutaneous manifestations of secondary syphilis span a wide spectrum and mimic those of other dermatoses. This may be particularly evident in patients with HIV. Such deviations from the expected typical papulosquamous eruption may present a diagnostic challenge and delay diagnosis and therapy. Given the increasing incidence of syphilis among the immunosuppressed patient population, recognition of atypical cutaneous manifestations is critical for adequate management. We review a range of cutaneous manifestations of secondary syphilis and the skin diseases it may mimic.