GUD syndrome | Etiologic agent | Classic ulcer characteristics | Incubation | Pain | Adenopathy |
HSV | HSV-1 and HSV-2 | Multiple small grouped ulcers; erythematous base. Occasionally, single lesions/fissures can be seen | 2 to 7 days | Usually painful; can be painless or pruritic | Reactive painful nodes common |
| Vesicles can open, forming shallow ulcers/erosions that may coalesce | | | |
Syphilis | Treponema pallidum | Indurated, smooth firm borders | 7 to 90 days | Usually painless; rarely can be painful | Firm, rubbery nodes |
| Clean base | | | Not tender |
| Heals spontaneously | | | Regional |
| Usually singular, although multiple chancres can occur | | | Discrete |
Chancroid | Haemophilus ducreyi | Sharply circumscribed or irregular, ragged undermined edges | 3 to 10 days | Marked | 50 percent with inguinal adenopathy |
| Not indurated | | | Usually unilateral |
| Base may have gray or yellow exudate | | | Often painful |
| Multiple ulcers | | | May suppurate/rupture |
LGV | Chlamydia trachomatis L1-L3 | Usually not observed | 5 to 21 days | Usually painless | More common in males |
| Small and shallow | | | Matted clusters |
| Rapid spontaneous healing | | | Unilateral or often bilateral |
| | | | Large painful fluctuant "buboe" |
| | | | Painful groove sign |
| | | | Sinus tracts common |
Granuloma inguinale | Klebsiella granulomatis | Extensive, progressive | 7 to 90 days | Usually painless | Pseudobuboes |
| Granulation-like tissue | | | |
| Rolled edges | | | |