A man presents to a dermatologist because of a severe mucocutaneous rash that involves most of his body,including his palms and soles. Questioning reveals that he is a merchant marine who several months previously had an encounter with a prostitute in Southeast Asia. Which of the following is the most likely causative agent of this rash?
Herpes simplex I
Herpes simplex II
HIV
Treponema pallidum
The rash described is that of secondary syphilis, caused by Treponema pallidum. Involvement of palms and soles by a rash is unusual, and secondary syphilis should come to mind. Not all patients with secondary syphilis have a severe form of the rash, and consequently some cases are missed. Primary syphilis takes the form of a painless, button-like mass called chancres. Teiary syphilis, which is now rare, has a propensity for involving the aoa and central nervous system and can also cause "gummas" (granulomatous-like lesions) in many sites, notably including liver and bone. Herpes simplex I usually causes perioral Herpes simplex II usually causes genital vesicular lesions. HIV does not itself cause a rash, although coinfection with other organisms can result in a rash. Ref: Ray C.G., Ryan K.J. (2010). Chapter 37. Spirochetes. In C.G. Ray, K.J. Ryan (Eds), Sherris Medical Microbiology, 5e.