Chancre

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Chancres (shang-ker) on the penis due to a primary syphilitic infection.

A chancre is a painless ulceration 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. Chancres transmit the sexually transmissible disease of syphilis through direct physical contact. These ulcers usually form on or around the anus, mouth, penis, and vagina. Chancres may diminish between three to six weeks without the application of medication.

In addition, chancres are associated with the sleeping sickness, African trypanosomiasis, subsequent to the bite of a tsetse fly.

[edit] Comparison with Chancroid

There are many differences and similarities between the conditions chancre and chancroid (reference 1 and 2)

Similarities

Both originate as pustules at the site of inoculation, and progress to ulcerated lesions
Both lesions are typically 1-2 cm in diameter
Both lesions are caused by sexually transmissible organisms
Both lesions typically appear on the genitals of infected individuals
Both lesions can present at multiple sites and with multiple lesions

Differences

Chancre is a lesion typical of infection with the bacterium that causes syphilis, Treponema pallidum
Chancroid is a lesion typical of infection with the bacterium Haemophilus ducreyi
Chancres are typically painless, whereas chancroid are typically painful
Chancres are typically non-exudative, whereas chancroid typically have a grey or yellow purulent exudate
Chancres have a hard (indurated) edge, whereas chancroid have a soft edge
Chancres heal spontaneously within three to six weeks, even in the absence of treatment
Chancres can occur in the pharynx as well as on the genitals