Nodular Syphilis Seen in an HIV-Positive Man: A Case Study.

Syphilis is becoming an increasingly concerning sexually transmitted infection in the primary care setting with a precipitous rise in cases in the USA over the past decade according to the CDC surveillance data. This rise in cases is particularly relevant in military medicine as the greatest increase in cases is among adults in their 20s. Nodular syphilis is a rare presentation of the secondary stage of syphilis, and contrary to the well-known maculopapular rash seen with syphilis infection, little is known about effective treatment of nodular manifestations of the disease. We present a case of a 54-year-old HIV-positive man with nodular secondary syphilis effectively treated with an empiric 2-week course of oral doxycycline. Initial differential diagnosis included erythema nodosum, arthropod vector disease, skin infection, and erythema elevatum diutinum. Biopsy demonstrated granulomatous dermatitis, and serology revealed positive Treponema pallidum antibodies with a rapid plasma reagin of 1:256, confirming the diagnosis of secondary syphilis with granulomatous dermatitis. This case indicates that clinicians should consider this unusual cutaneous presentation of secondary syphilis when evaluating patients with nodular skin lesions, especially in high-risk individuals.