1996 Rectal Syphilis Presenting as Painless Hematochezia

Abstract

INTRODUCTION: Diagnosing syphilis is challenging and rectal syphilis is a rare presentation. Patients with rectal syphilis can be asymptomatic or have anal pruritus, tenesmus, urgency of defecation, or anal discharge. We describe a case of rectal syphilis presenting with painless hematochezia. CASE DESCRIPTION/METHODS: A 40-year-old man with a history of HIV not on antiretroviral therapy and multiple sexually transmitted diseases presented with 7 days of painless hematochezia. He reported that 17 years ago he was infected with Chlamydia, gonorrhea and syphilis, which were all treated. He last had anal intercourse one-year prior. Starting 8 months ago, the patient had daily 7–10 non-bloody formed bowel movements that decreased the week prior to presentation to 3–5 bowel movements daily when his hematochezia began. Over the past month he has had progressive fatigue limiting his functional capacity and a 10-lb weight loss. He did not have nausea, vomiting, abdominal pain, constipation, or fever. Upon presentation, vital signs were within normal limits. He was well-developed and well-nourished with unremarkable abdominal, perianal and digital rectal examinations. CBC showed normocytic anemia. CD4 count was 204 with HIV viral load of 1.5 million copies/mL. CMV viral load was undetectable. Testing for Chlamydia and gonorrhea were negative. Notably his rapid plasma regain (RPR) was non-reactive. Stool studies including culture, ova and parasites were unremarkable. CT scan of the abdomen and pelvis showed mild asymmetric rectal thickening. A colonoscopy was performed which was significant for a 4-mm rectal submucosal nodule with ulceration and surrounding erythematous tissue. Hematoxylin and eosin stain of the biopsy was negative for malignancy, but Warthin-Steiner (silver) stain was positive for spirochetes. There was concern for rectal syphilis and the patient was referred for treatment. DISCUSSION: The differential diagnosis of spirochetes in the intestines include Treponema and Brachyspira. Patients with successfully treated syphilis can have reactive non-treponemal and treponema serum testing, but the titers wane over time. In HIV and syphilis co-infected patients serum testing has a lower sensitivity and specificity. Therefore despite the findings of blood testing, direct visualization helps with diagnosis. If there is any concern for syphilis, such as in this patient, treatment with penicillin is used to prevent sequelae of the disease (e.g. neurosyphilis or gummas).