Primary syphilitic chancre in the rectum

A 50-year-old homosexual man was referred for rectal bleeding with the passage of red blood, increased bowel habit, and rectal discomfort for 15 days, without constitutional or febrile symptoms. A colonoscopy performed 6 years previously had been normal. Examination revealed a soft nipple-shaped papillary lesion with traces of blood on rectal palpation. The results of his blood count and tests for liver and renal function, ferritin, human immunodeficiency virus (HIV), and carcinoembryonic antigen (CEA) were all normal, but he had an elevated C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). A thoracoabdominal computed tomography (CT) scan showed a reduction in the caliber of the rectum, with locoregional, abdominal, and inguinal lymphadenopathy ([Fig. 1]).

Fig. 1 Abdominal computed tomography (CT) scan in a 50-year-man with rectal bleeding and abdominal pain over a 15-day period showing thickening of the rectal wall and enlargement of regional lymph nodes.

Colonoscopy showed a rectal ulcer with a fibrinous surface and elevated, smooth, erythematous edges ([Fig. 2 a]). A biopsy taken from the ulcer did not indicate the presence of any neoplastic cells but was compatible with an active acute ulcer. As we therefore suspected a diagnosis of syphilitic chancre, he was started on treatment with intramuscular penicillin, which resulted in clinical and endoscopic improvement ([Fig. 2 b]). A rapid plasma reagin (RPR) serology test was positive before treatment, but was negative when repeated after treatment. Staining for spirochetes was negative.

Fig. 2 Conventional colonoscopy views showing: a at presentation, evidence of an ulcer in the rectum, with elevated, erythematous edges, and traces of fibrin in the ulcer bed, in an otherwise normal-looking mucosa, consistent with a primary syphilitic chancre in the rectum; b at follow-up 2 months later, almost complete healing of the rectal ulcer.

The primary chancre of syphilis appears after an incubation period of 2 – 3 weeks at the site of Treponema pallidum inoculation as a result of sexual contact. It is often associated with lymphadenopathy. The primary chancre heals spontaneously within 3 – 6 weeks, leaving a slightly indurated scar.

There are only a few published cases of primary syphilis in the rectum [1] [2] [3]. In our patient, the appearance of the primary chancre resembled that seen in other locations, but reports suggest it is commonly confused with rectal neoplasm or inflammatory bowel disease [4] [5].

This etiology should be suspected particularly in young homosexual men, and it is important to rule out co-infection with HIV. The diagnosis is made by treponemal tests (venereal disease research laboratory [VDRL] and RPR tests), non-treponemal tests, dark-field microscopy, or immunostaining. The treatment of choice is penicillin.

Endoscopy_UCTN_Code_CCL_1AD_2AD

Competing interests: None

• References

• 1 Song SH, Jang I, Kim BS et al. A case of primary syphilis in the rectum. J Korean Med Sci 2005; 20: 886-887
• 2 Bassi O, Cosa G, Colavolpe A et al. Primary syphilis of the rectum–endoscopic and clinical features. Report of a case. Dis Colon Rectum 1991; 34: 1024-1026
• 3 Febbraro I, Manetti G, Balestrieri P et al. Rectal cancer or rectal chancre? Beware of primary syphilis. Dig Liver Dis 2008; 40: 579-581
• 4 Zhao WT, Liu J, Li YY. Syphilitic proctitis mimicking rectal cancer: A case report. World J Gastrointest Pathophysiol 2010; 1: 112-114
• 5 Tigchelaar CK, Brosens LA, Seldenrijk CA. An unusual rectal mass. Gastroenterology 2012; 143: 16-17