Secondary syphilis as a single annular plaque on the penis mimicking granuloma annulare

Abstract

A 44-year-old homosexual man currently on antiretroviral therapy for HIV infection presented with a three month history of a single annular red plaque of two cm diameter with central clearing and raised borders on the penis, associated with mild pruritus [Figure 1]. There were no lesions in the oral cavity, palms, or soles. Lymphadenopathy and systemic symptoms were absent.Histopathological examination revealed a dense dermal infiltrate composed of lymphocytes and plasma cells in a lichenoid pattern with epitheliotropism. Immunohistochemistry showed the presence of Treponema pallidum. Rapid plasma reagin (RPR) test was reactive in 1:32 dilution and fluorescent treponemal antibody absorption test was positive. The CD4 lymphocyte count was within normal limits. A diagnosis of secondary syphilis was made and the patient received 2.4 million units of penicillin G benzathine weekly for 3 weeks, despite the existing guidelines preferring a single-dose therapy, leading to a complete healing of the lesion. Serology performed 3 months after treatment showed an improved RPR of 1:4 dilution. Declaration of patient consentThe authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Petaloid dermatosis affecting the scalp and genitalia

“…2 Lesions in annular secondary syphilis often occur close to the angle of the mandible and frequently spare the palms and soles. [3][4][5] Secondary syphilis typically presents without lymphadenopathy and often affects the genitalia. 5…”

Annular genital lesions, not an unusual presentation of secondary syphilis

“…Differential diagnosis needs to be made with other annular lesions such as granuloma annulare, annular lichen planus, annular psoriasis, scabies, and dermatophytosis 4 . There have been few cases of annular syphilis localized on the genital area; specifically, eight cases have been reported so far, 4–10 some of them presenting as a solitary plaque 4,8 . Only three of these presented scrotal lesions 4,5 …”

“…4 There have been few cases of annular syphilis localized on the genital area; specifically, eight cases have been reported so far, 4-10 some of them presenting as a solitary plaque. 4,8 Only three of these presented scrotal lesions. 4,5 Biopsies were performed in six patients showing lymphohistiocytic and plasmocytic infiltrates and spirochetes.…”

Atypical presentation of secondary syphilis: annular lesions in an elderly patient

“…The clinical protocol and therapeutic guidelines for sexually transmitted infections 5 recommend the use of benzathine benzylpenicillin 2.4 million international units (IU), intramuscularly (IM), in a single-dose (1.2 million in each gluteus). However, most treated cases report a better outcome with the administration of three doses 6 , 7 . The dermatologist, in this case, chose to treat the suggestive secondary syphilis with benzathine penicillin and a total dose of 4,800,000 IU as a precaution.…”