Syphilis, caused by Treponema pallidum, a microaerophilic spirochete, is a systemic, chronic sexually transmitted disease. Secondary syphilis generally occurs 2 to 10 weeks after the primary active period. Symptoms vary; many present with mild constitutional complaints, including headache, nausea, malaise, loss of appetite, fatigue, fever, and aching bones. Acute syphilitic meningitis may occur in a small percentage of patients. The skin eruption evolves over time. The initial rash consists of bilaterally symmetric, discrete, round macules, 5 to 10mm in diameter on the trunk and proximal extremities. Color varies depending on the patient's skin color: light-skinned individuals tend to have pale red to pink lesions while the macules are pigmented in dark-skinned patients. Red papular lesions, 3 to 10 mm in diameter appear several days to weeks later. Palms and soles are often involved and the lesions tend to become necrotic. Alopecia may also develop. Of note, the skin eruption may be subtle enough that a quarter of patients don't notice changes. Other findings that may develop are superficial mucosal erosions on the palate, pharynx, laraynx, glans penis, vulva, anal canal, or rectum, condyloma lata, iritis, periostitis, nephiritis, hepatitis, and ulcerative colitis.

The gold standard for treating syphilis is penicillin. Doxycycline is an alternative for patients with a penicillin allergy. Early diagnosis and treatment are the keys to curing secondary syphilis. Untreated secondary syphilis may result in late complications in 30% of patients. Complications include aortitis, aneurysms, neurosyphilis, and destructive skin and bone lesions.