<unk>  on the underside of the penis A<unk>  ( ) is a painless genital ulcer most commonly formed during the primary stage of syphilis. This infectious lesion forms approximately 21 days after the initial exposure to Treponema pallidum, the gram-negative spirochaete bacterium yielding syphilis.<unk> s transmit the sexually transmissible disease of syphilis through direct physical contact. These ulcers usually form on or around the anus, mouth, penis and vagina.<unk> s may diminish between four and eight weeks without the application of medication.<unk> s are also associated with the African trypanosomiasis (sleeping sickness), surrounding the area of the tsetse fly bite.
Chancre
Saddle sore
Enanthem
Blister
Oscar 
Keratitis
Burn 
Burn