Psoriasis guttata with palmoplantar involvement clinically mimicking secondary syphilis.

Papulosquamous eruptions involving the palms and soles are thought to be particularly suggestive of secondary syphilis. Alternative diagnoses exist, however, and include psoriasis guttata, atypical pityriasis rosea, and pityriasis lichenoides chronica (PLC). We describe the case of a patient with an abrupt onset of psoriasis guttata and extensive palmoplantar involvement. Results of serologic testing were negative for treponemicidal antibodies. Results of histopathologic examination demonstrated psoriasiform dermatitis with neutrophils in the epidermis; plasma cells were absent. Spirochetes were not demonstrated in a tissue sample using silver or immunohistochemical stains for Treponema pallidum. A broad differential diagnosis is required when evaluating papulosquamous eruptions with palmoplantar involvement. Although not well referenced in the medical literature, psoriasis guttata can indeed cause palmoplantar lesions that mimic those of secondary syphilis.