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Revista Española de Enfermedades Digestivas

Print version ISSN 1130-0108

Rev. esp. enferm. dig. vol.109 n.3 Madrid Mar. 2017 



Primary chancre in the rectum: an underdiagnosed cause of rectal ulcer



Key words: Syphilis. Ulcer. Colonoscopy.



Dear Editor,

An increase in the incidence of syphilis has been reported, particularly in homosexual men infected with the human immunodeficiency virus (HIV) (1). However, primary rectal syphilis is rare, making it a diagnostic challenge.


Case report

We report the case of a 35-year-old homosexual man with a previous history of HIV, who presented with a two-week history of intermittent bloody stools. Rectal digital examination revealed a palpable mass with a rough surface and bleeding. Colonoscopy showed an irregular rectal ulcer with a fibrinous surface and marked mucosal friability involving half of the rectal circumference (Fig. 1A). Histological examination demonstrated a chronic inflammatory cell infiltration predominantly composed of plasma cells, with severe cryptitis and the absence of neoplastic cells. The Warthin-Starry stain allowed the direct visualization of spirochetes (Fig. 1B).



Both the Treponema pallidum hemagglutination assay (TPHA) and the rapid plasma reagin (RPR) were positive. After treatment with benzyl penicillin, complete resolution of symptoms was achieved and the rectal ulcer disappeared.



Rectal syphilis is one of the great masquerades due to its variable symptoms, including itching, bleeding, tenesmus, urgency of defecation, and anal discharge, which may be purulent, mucoid, or blood stained (3).

Dark-field microscopy may be used in the initial diagnostic analysis, however, dark-field microscopy of exudates from a rectal ulcer may be inaccurate because of contamination from commensal spirochetes found in the normal flora of the rectum. The diagnosis of rectal syphilis is based primarily on endoscopic biopsy of anorectal lesions and serology. If infectious proctitis is suspected, water could be used as the only lubricant on anoscopy as many of the commercially available lubricants contain bacteriostatic agents; however, there is not enough evidence to definitively assess this intervention (4).

The clinical presentation of a primary chancre can mimic other common conditions such as inflammatory bowel diseases, rectal solitary ulcer or malignancy. Long-term prognosis of rectal syphilis is excellent but it can be influenced by patient and physician delays. Therefore, a high level of suspicion, particularly in HIV-positive homosexual patients, is crucial in order to avoid incorrect diagnosis, and delayed antibiotic therapy (3,5).


Francia Díaz-Jaime, Carla Satorres-Paniagua and Marco Bustamante-Balén
Digestive Endoscopy Unit. Department of Gastroenterology.
Hospital Universitari i Politècnic La Fe. Valencia, Spain



1. Arnold C, Limketkai B, Illei P, et al. Syphilitic and lymphogranuloma venereum (LGV) proctocolitis: Clues to a frequently missed diagnosis. Am J Surg Pathol 2013;37:38-46. DOI: 10.1097/PAS.0b013e31826a523e.         [ Links ]

2. Febbraro I, Manett G, Balestrieri P, et al. Rectal cancer or rectal chancre?: Beware of primary syphilis. Dig Liver Dis 2008;40:579-81. DOI: 10.1016/j.dld.2007.09.004.         [ Links ]

3. Cha J M, Choi SI, Lee J I. Rectal syphilis mimicking rectal cancer. Yonsei Med J 2010;51(2):276-8. DOI: 10.3349/ymj.2010.51.2.276.         [ Links ]

4. Voth ML, Akbari RP. Sexually transmitted proctitides. Clinics in colon and rectal surgery. Clin Colon Rectal Surg 2007;20(1):58. DOI: 10.1055/s-2007-970201.         [ Links ]

5. Hoentjen F, Rubin D. Infectious proctitis: When to suspect it is not inflammatory bowel disease. Dig Dis Sci 2012;57:269-73. DOI: 10.1007/s10620-011-1935-0.         [ Links ]