Adenomas of the large bowel are early-stage lesions. Depending on their advancement, low-, moderate- and high-grade dysplasia has been distinguished. Adenocarcinoma is currently the third most commonly diagnosed cancer in humans. It develops as a result of high-grade dysplasia progressing into cancer. Solitary rectal ulcer syndrome (SRUS), which was first described by Cruveilhier in 1829 is another condition, with a different mechanism of formation and clinical course (1-4). The wide variety of pathologies and uncertain endoscopic images prompt colonoscopy, biopsy and resection of all suspicious lesions during the examination. Technological advances have allowed the use of minimally invasive techniques, including natural orifice minimally invasive surgery (3, 4). Transanal endoscopic microsurgery (TEM) is an excellent tool for resecting lesions located up to 20 cm from the anal verge. Many papers have been written emphasising the superiority of this approach over classical surgery involving low anterior resection or abdominoperineal amputation of the rectum (5-7).

We describe a case of a 39-year-old woman who reported to a proctology clinic due to incomplete rectal prolapse. She had been treated for this reason at an external centre for 4 years. She was first diagnosed with haemorrhoidal disease (at treatment onset), and then with rectal prolapse. She had family history of surgically-managed rectal prolapse both in her mother and sister. The patient reported that she regularly passed stool with bright red blood and mucus. Furthermore, she experienced a feeling of incomplete bowel movement, anal pruritus, as well as uncontrolled rectal prolapse during coughing or sneezing. Digital rectal examination (DRE) revealed grade III/IV haemorrhoids, a palpable rectal mass on the posterior wall, and normal anal sphincter tone. The patient was admitted to the Department of Surgery for urgent diagnosis. Computed tomography (CT) of the chest, abdominal cavity and pelvis was performed, without finding any abnormalities. CEA marker was 2.68 ng/mL. Colonoscopy revealed an approx. 2-3 cm palpable hard thickening on the posterior wall behind the sphincters. The endoscopic image was inconclusive. Rectal tumour? Solitary rectal ulcer? Samples were collected. Histopathological examination of superficial samples showed tubular adenoma of the colonic mucosa with low-grade dysplasia.