We report the case of an immunocompetent 23-year-old Caucasian woman, with symptoms including rectal bleeding, tenesmus and epreint, 6 months after an anal sexual trauma. The rectal examination showed a hardened, inflammatory and painful anal margin, associated with stenosis of the anal canal, suggesting abscess. The neurological examination showed numbing of the chin. Pelvic MRI and CT scan confirmed a bulky posterior tissular pelvic mass more than 7 cm in diameter, infiltrating the rectum and the anal canal. Final diagnosis confirmed by biopsy performed during rectosigmoidoscopy was an Epstein-Barr Virus-Associated Burkitt's lymphoma. Chemotherapy resulted in rapid regression of the tumoral mass.