EP392 - Different modalities used in the investigation of anorectal lesions: a case report and discussion

Abstract Introduction Endoanal ultrasound scan (EAUS) /MRI rectum followed by early open/endoscopic, resection/biopsy for histology are important to plan management of all anorectal lesions. Here, we report an incidentally found inter-sphincteric lesion investigated with both EAUS and MRI scans, followed by excision. Case report A 55-year-old patient presented with post-menopausal bleeding and was investigated with an MRI pelvis which confirmed the causative subserosal fibroid. An incidental 15x12 mm focal soft tissue lesion at 2 o’clock between the internal and external anal canal sphincters was also picked up by the consultant GI radiologist. Her colonoscopy was normal but her digital rectal examination revealed a palpable submucosal elongated pea shaped lump at 2 o’clock. A lower GI specialist nurse performed an EAUS which suggested the lesion to be at 10 o’clock. At examination under anaesthetic (EUA), the mass in the inter-sphincter anal canal was confirmed at 2 o’clock, and excised after careful dissection from its intersphincteric location; histology confirmed a leiomyoma. The patient recovered well from the procedure. Discussion MRI and endoanal ultrasound are key imaging modalities in the diagnosis of rectal masses. EAUS provides more accurate assessment of depth of tumour invasion compared to MRI, and its relation to the anal sphincters; however, the scans are highly operator-dependent, as we found, and need to be interpreted with the benefit of clinical examination. Conclusion MRI and EAUS are complimentary in investigating rectal masses; however clinical examination, (especially under anaesthetic), as well as histology, gives the best information to plan subsequent management of common and unusual lesions (such as this) in the anorectum.