C. Secondary syphilis
The patient’s symptoms and laboratory findings are consistent with a diagnosis of secondary syphilis, which is caused by the spirochete bacterium Treponema pallidum. T. pallidum is a sexually transmitted organism and manifests with diverse symptoms depending on the stage of the disease.
Primary syphilis presents as a hard, painless chancre on genital tract tissues or in the oral cavity. Chancres appear approximately three weeks after exposure to T. pallidum, but the lesions may not be obvious to the patient as they are painless. Chancres resolve spontaneously, followed by an asymptomatic period that may persist for up to 24 weeks. Subsequently, the spirochete disseminates throughout the body via the blood and lymph, causing systemic symptoms seen in secondary syphilis.
Secondary syphilis is typically associated with a dull, red maculopapular rash that can appear on any part of the body, often including the palms of the hands and soles of the feet, as was evident in this case. Both the primary and secondary syphilitic lesions contain numerous, viable spirochetes and are therefore highly contagious. The secondary stage of disease is often accompanied by multiorgan involvement, resulting in lymphadenopathy, nephritis, chorioretinitis, hepatitis, meningitis or other manifestations.
After the secondary lesions heal, the disease enters a latent phase, which can last many years. Tertiary syphilis is characterized by nervous system and cardiac involvement, and the appearance of granulomatous lesions (gummas) in the liver, skin and bones. The disease in the tertiary stage is very difficult to treat. Diagnosis of syphilis is serological, involving detection of treponemal antibodies. The preferred treatment for syphilis is with penicillin since T. pallidum has not yet developed resistance to this antibiotic.
Treatment with penicillin in this case resulted in resolution of the infection. With a diagnosis of any sexually transmitted infection, such as syphilis, it is important to test for the concomitant presence of other sexually transmitted pathogens, including Neisseria gonorrhoeae, Chlamydia trachomatis and human immunodeficiency virus (HIV).