Which treponemal infection is limited to the skin in its presentation?

Pinta is a treponemal infection that is specifically characterized by its skin manifestations. It is caused by the bacterium Treponema pertenue and primarily affects the skin, leading to the development of lesions such as macules, papules, and plaques. These lesions are often disfiguring but do not penetrate deeper into the body or cause systemic disease, which is a key distinction of Pinta from other treponemal infections.

In contrast, Yaws, Bejel, and Syphilis all have broader implications beyond the skin. Yaws typically presents with skin lesions initially but can progress to involve bones and joints. Bejel tends to affect mucous membranes and can result in more extensive systemic involvement if not treated. Syphilis, particularly in its later stages, can lead to significant systemic effects, affecting multiple organs and structures.

Pinta's limited presentation strictly to the skin differentiates it and makes it the correct answer to the question of which treponemal infection is confined to skin symptoms.