LAUSR

A 19-year-old heterosexual man presented with several well-demarcated, red and scaly facial skin lesions. Five weeks previously, he had been started on ustekinumab 45 mg to treat severe joint symptoms, as he had a 5year history of psoriatic arthritis and plaque psoriasis. Previous psoriasis treatments had included subcutaneous methotrexate and adalimumab applications, which were both stopped because of lack of response and severe adverse effects. Ustekinumab was administered subcutaneously at weeks 0 and 4, and was due to be administered every 12 weeks thereafter. After the second ustekinumab administration, there was complete clearance of the patient’s joint symptoms. On physical examination, several well-demarcated, red, scaly and thickened skin lesions, 10–13 mm in diameter, were seen on the patient’s face (Fig. 1). Other parts of his body were not affected. He denied having any pain, itching, fever or general symptoms. His weight was 84 kg and body mass index 25.6. Smear testing ruled out mycotic infections. Histological findings of a skin biopsy were consistent with an acanthopapilloma. A relapse of plaque psoriasis was initially suspected, and moisturizing local therapy only was recommended. After another week, there was worsening of symptoms with development of new facial skin lesions. A detailed medical history revealed that the patient had had unprotected heterosexual intercourse approximately 6 weeks prior to ustekinumab initiation. Serological tests were performed to exclude sexually transmitted diseases (STDs), including human immunodeficiency virus (HIV), hepatitis B and C viruses, and syphilis. The Treponema palladium haemagglutination assay (TPHA: <1 : 80) titre was elevated (1 : 640) and the fluorescent treponemal antibody absorption test for IgM (IgM-FTA-ABS) was positive. Given the serological results, patient history and the clinical manifestations, early secondary syphilis was diagnosed. Skin alterations indicative for primary syphilis had not been noted by the patient in the past. As the patient reported being allergic to penicillin, he was started on ceftriaxone 2 g intravenously (IV) once daily for 18 days. To reduce the risk of development of a Jarish–Herxheimer reaction, prednisolone 80 mg IV was given once before the first antibiotic treatment. Within 1 month, complete remission of the syphilitic skin lesions was seen. Follow-up serological testing revealed the same elevated TPHA titre (1 : 640), but IgM-FTA-ABS was negative, consistent with adequately treated syphilis. Ustekinumab treatment was continued with no further side effects. Ustekinumab, a human interleukin-12/23 monoclonal antibody, shows significant therapeutic efficacy in moderate to severe plaque psoriasis and psoriatic arthritis, and has a good safety profile. However, it may allow infections or reactivation of latent infections. As the clinical manifestation of secondary syphilis may mimic a number of other skin diseases, infection with or reactivation of syphilis during biologic therapy can be easily overlooked or misdiagnosed. The reported patient developed his psoriasiform eruptions approximately 11 weeks after unprotected heterosexual intercourse, which was considered the cause of infection. In this case, with regard to the ongoing immunomodulatory therapy, the development of secondary syphilis may have been either facilitated or accelerated, and the skin manifestations may have been more severe compared with the natural course of this bacterial infection. Reactivation of a latent syphilis infection due to ustekinumab treatment could be possible, but seems unlikely because of the short time Correspondence: Dr med Ugur Uslu, Department of Dermatology, Universit€atsklinikum Erlangen, Ulmenweg 18, D-91054 Erlangen, Germany E-mail: [email protected]