CPC04 A rare rupioid rash

Abstract

A 59-year-old man was referred to an urgent skin cancer dermatology clinic with a 4-month history of multiple skin lesions on his trunk, arms and face. The lesions were painful, increasing in size, bleeding and oozing serous fluid. The patient reported being otherwise systemically well, with a history of mild eczema and a background of high alcohol intake. On examination, he had a striking rash with numerous large rupioid plaques with thick crusting and surrounding erythema on the trunk and limbs. Smaller plaques were seen on the face and neck. An infective aetiology was favoured with an initial differential diagnosis of ecthyma or atypical mycobacterial infection. A biopsy was taken, as well as screening blood tests. Treponemal antibodies were detected; rapid plasma reagin was reactive (1 : 32), as was Serodia Treponema pallidum particle agglutination test (1 : 1280), suggesting active syphilis infection. His biopsy demonstrated granulomatous inflammation, associated with neutrophils, plasma cells and increased mucin deposition. Immunohistochemical staining for T. pallidum confirmed corkscrew-like organisms within the basal epidermis and upper dermis, consistent with secondary syphilis; screening for concurrent HIV infection was negative. The patient was referred to a local genitourinary clinic for treatment with benzylpenicillin and for full sexual health screening. The word ‘rupioid’ describes oyster or limpet shell-shaped thick keratotic lesions and is derived from the Greek word rhupos, meaning ‘filth’. Differential causes for rupioid lesions include cutaneous T-cell lymphoma, psoriasis, scabies and syphilis. Rupioid syphilis is also termed ‘malignant syphilis’ or ‘Lues maligna’, describing well-demarcated plaques with thick, lamellate and adherent crusts. It is most frequently encountered in HIV-positive patients; in HIV-negative patients, the associated comorbidities are diabetes, alcoholism, drug abuse, psoriasis and hepatitis. Typically, there is rapid clinical improvement once antibiotic treatment is administered, but episodes of Jarisch Herxheimer reaction are reported. Syphilis diagnoses have tripled over the last 10 years, with cases in the heterosexual population rising most rapidly. Dermatologists have a pivotal role to play in diagnosing primary and secondary syphilis, thereby preventing the long-term sequelae of tertiary syphilis and controlling the rising prevalence of the disease in the general population. This case highlights a striking and rare manifestation of secondary syphilis which, once seen, will not be forgotten.