Erythema multiforme caused by Treponema pallidum in a young patient with human immunodeficiency virus infection

Abstract

Erythema multiforme (EM) is usually caused by drug reactions or virus infection. We report a case of secondary syphilis presenting as EM in an HIV-infected patient, proved by immunohistochemical staining, which is rare in the literature. It is valuable to determine the etiology of EM to optimize treatment.

FIG. 1.

Numerous coin-sized target lesions with confluent patches presenting on the patient's entire body.

FIG. 2.

Vacuolar degeneration of the basal cell layer with a few apoptotic keratinocytes and perivascular lymphohistiocyte infiltration were noted in the lesion (hematoxylin and eosin; original magnification, ×400).

FIG. 3.

(A) Abundant intraepidermal spirochetes were identified in the area of vacuolar degeneration (immunohistochemical staining with a polyclonal antibody to spirochetes; magnification, ×400). (B) Spirochetes were not found in the paralesional site, which showed little inflammation in the hematoxylin-and-eosin section (immunohistochemical staining with a polyclonal antibody to spirochetes; magnification, ×400).