BI21 Lues maligna mimicking pyoderma gangrenosum and cutaneous lymphoma

A 44-year-old man was referred for 2 months of erythematous ulcerative papules and plaques on the scalp, face and lower legs. The lesions started as painful ‘pimples’. He also reported fever and chills. He had a 5-year history of well-controlled HIV on antiretroviral therapy since diagnosis and a prior history of recurrent syphilis. Exam showed a large violaceous plaque on the right cheek with surrounding erythematous papules and an additional erythematous papule on the left ear. On the bilateral ankles and calves were four ulcers with necrotic centres and purple borders. The differential diagnoses included pyoderma gangrenosum and cutaneous lymphoma. A punch biopsy of the right zygomatic area showed dermatitis with a dense, diffuse plasma cell infiltrate suggestive of syphilis. The acid-fast bacteria (AFB), periodic acid–Schiff with diastase (PAS-D), and spirochete stains were all negative. Rapid plasma regain (RPR) was reactive at 1 : 4096. HIV was detected at < 30 copies per mL. Absolute CD4 T-cell count was 529 cells per μL. AFB and fungal cultures were negative, and bacterial culture showed rare Staphylococcus aureus. Although the spirochete stain was negative, it is only 70% sensitive and the positive RPR with histopathology supportive of syphilis in a patient who was positive for HIV confirmed the diagnosis of lues maligna. The patient received one dose of 2.4 million units of intramuscular penicillin G benzathine. He continued empiric doxycycline 200 mg daily, which had previously been initiated, and continued doxycycline postexposure prophylaxis after diagnosis. The patient reported healing with no new lesions 3 weeks after treatment. A new question brought on by this case is whether prior history of recurrent syphilis infection has a role in developing lues maligna. This patient in particular required syphilis treatment four times in the 3 years leading up to his presentation. Current literature describes a patient who was treated for secondary syphilis, then reinfected with malignant syphilis. However, further research is needed to elicit whether recurrent syphilis infections increase the chances of severe infection or malignant syphilis.