Primary syphilis is defined by the presence of a chancre that develops at the site of inoculation. The initial lesion usually appears approximately three weeks after infection, although the incubation period can range from 10 to 90 days. The primary chancre appears as a single painless papule, and can often go unnoticed by the patient. After a short time, the lesion will become indurated, and then erode and ulcerate. The lesion generally remains clean and dry unless secondary infection occurs. Regional lymphadenopathy commonly presents within one week of the chancre's appearance. The lesion will spontaneously resolve in a period of three to six weeks, although adenopathy may persist slightly longer. Darkfield examination of exudate from a lesion will demonstrate numerous motile spirochetes and is the gold standard for diagnosis.
Although the site of inoculation usually involves the anogenital region, with the external genitalia being the most common location for a primary chancre, syphilis also presents with head and neck manifestations. After the external genitalia, the lips are the next most common site of chancre formation (Fig. 2). Inoculation can occur throughout the oral cavity, with the tongue and tonsil most likely to be involved. Lesions of the oral cavity are more likely to become superinfected. Though much more rare, chancres involving the
FIGURE 2 A chancre is the defining lesion of primary syphilis. This image demonstrates a chancre of the lip, the most common site of presentation after the external genitalia. Source: Courtesy of the CDC Public Health Image Library.
larynx and the nose have also been reported. Cervical adenopathy is frequently associated with such primary infections of the head and neck region.
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