Below are a few pictures of a few manifestations of the different stages of Syphilis.
Primary Syphilis — Chancre: Painless ulcer with heaped edges at site of inoculation:

elsevierimages

dermnet.com

img.tfd.com

top-10-list.org
Secondary Syphilis — Rash: Comes in many varieties. Any rash with involvement of palms & soles is very suggestive. Some examples:

manbir-online.com

onlinemedicinetips.com

biologyreference.com

medicalpictures.net
NOT Syphilis: This is Pityriasis Rosea. But there’s no way to tell!!! Never diagnose “PR” without drawing syphilis serology.

dermweb.com
Secondary Syphilis — Mucus Patches: Plaques or erosions on mucus membranes.

students.cis.uab.edu

cdn.hivguidelines.org
Secondary Syphilis — Condylomata Lata: Nodules or verrucous lesions in intertriginous areas or mucus membranes.

library.med.utah.edu

dermis.net

hellenicdermatlas.com

3.bp.blogspot.com

www2.uni-jena.de
Tertiary Syphilis — Gumma: Heaped-up, disfiguring granulomas on skin, bone, or viscera [rarest form of 3° Syphilis].

manual-of-surgery.com

sciencephoto.com

ibmi3.mf.uni-lj.si

uhavax.hartford.edu