ANAL POLYP CAUSED BY SCHISTOSOMA MANSONI EGGS

Male patient, 27 years old, from Bahia. He presents with anal pain and bleeding, evolving with worsening pain and tenesmus. On physical examination, a posterior anal fissure progressing to a hardened nodular lesion was observed. Pelvic MRI showed findings of a subcutaneous nodular lesion without muscular extension, solid with regular contours, located in the anorectal area, measuring 3.3x2x1.8 cm. No colonoscopy or laboratory tests were performed. An excisional biopsy revealed rectal mucosa with granulomatous polypoid inflammation, associated with Schistosoma mansoni eggs. The patient showed improvement of symptoms at follow-up, treated with praziquantel after diagnosis. Intestinal schistosomiasis is a disease with a classic late manifestation due to egg deposition in the intestinal wall and liver, leading to portal hypertension and hepatomegaly. The acute form is less common and involves itching, cough, and abdominal pain. The most significant symptom is colitis due to egg infiltration in the submucosa and a foreign body reaction, which can chronically evolve into nodules, with eggs surrounded by intense granulomatous inflammation. This inflammatory infiltrate can cause necrosis, stenosis, or well-formed polyps. Rectal polyps are atypical and more commonly associated with S. mansoni, which has a tropism for the rectal mucosa and is more common in the Americas. Although S. japonicum in Asia is more strongly related to polyps and cancer. About 96.4% of nodules are distal to the ascending colon, with more than 80% occurring in the rectum. Similar cases in Brazil and Yemen involve healthy patients with endemic exposure. The Brazilian case is most similar to this one, describing an anal tumor with progressive growth and pain, granulomatous and fibrotic tissue involving the eggs and central necrosis. Cases in Asia follow the same histopathology, but present with symptoms of altered bowel habits, with the lesion not being the main complaint. In both reports, patients were treated with praziquantel and showed improvement. The patient did not undergo further tests, so it is not possible to compare rectal mucosa or involvement of other locations; however, the imaging findings indicate rectal lesions as the sole manifestation. In conclusion, despite being an uncommon manifestation, both the clinical epidemiological profile and histopathology are consistent with S. mansoni infection and pseudotumoral schistosomiasis.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
25 April 2025