Secondary syphilis manifesting as annular lichenoid plaques

Abstract

Background: Syphilis continues to be a diagnostic challenge as the myriad manifestations of secondary syphilis can mimic a lot many dermatological disorders. Annular Lichenoid syphilis is an uncommon entity, reported only occasionally in the penicillin era. We present the case of a 24-year-old man presenting with annular lichenoid lesions over face Methods & Materials: A 24-year-old male with multiple pink to brown coloured lesions over face since 1 month. At the same time he was being treated for acne vulgaris with tretinoin 0.025% cream and clindamycin 0.05% cream from private practioner. Lesion initially appeared as reddish coloured gradually spreading peripherally to become annular with central hyperpigmentation. Past history revealed homosexual unprotected sexual exposure with multiple partners, last passive exposure 1 month prior to onset of skin lesions. General and systemic examination was normal. On cutaneous examination there was evidence of multiple annular plaque over face with central hyperpigmentation. Also hyperpigmented macules over bilateral palms and soles, neck, chest, forearms, hands was present. Deep dermal tenderness was positive. Differential Diagnosis kept was Lichen Planus, Secondary Syphilis, Polymorphic light eruption disorderand Erythema Multiforme. Serological investigation showed Venereal disease research laboratory assay came out to be positive in the titres for the patient: 1:32, and Treponema pallidum haemagglutination for syphilis was Positive. Serology for Hepatitis B, and HIV was negative. Results: Biopsy from annular plaque showed interface dermatitis, perivascular and perieccrine plasma cell infiltrate and granuloma. Diagnosis kept was Secondary syphilis presenting as unusual annular lichenoid lesions was favoured. Three doses of Intramuscular Injection of Benzathine penicillin 2.4 million units was given. After 3 months all skin lesions subsided with persistence of post inflammatory hyperpigmentation over face. Conclusion: The presentations of syphilis, often described as “the great imitator,” can be varied and atypical. Thus prompt diagnosis and treatment is necessary.