A patient presents with a rash on his palms and soles. What condition could this indicate?

A rash on the palms and soles is characteristic of secondary syphilis, which typically occurs weeks to months after initial infection with Treponema pallidum, the bacteria that causes syphilis. During the secondary stage, the infection is disseminated throughout the body, leading to systemic symptoms and cutaneous manifestations.

The rash associated with secondary syphilis can present as red-brown spots or papules and often involves the trunk as well as the hands and feet. This systemic involvement is a hallmark of the secondary stage of syphilis, distinguishing it from primary syphilis, where the presentation is localized to the chancre site, and syphilitic chancre, which specifically refers to the genital ulcer of primary syphilis.

Although psoriasis can also cause skin lesions on the palms and soles, it does not typically present in conjunction with systemic symptoms or other signs indicative of an infectious disease. Therefore, the presence of a rash specifically located on the palms and soles, along with additional symptoms indicative of systemic involvement, strongly suggests secondary syphilis as the underlying condition.