LAUSR

A 32-year-old male underwent an elective colonoscopy for painless fresh bleeding per rectum. Bleeding was an isolated event over a few days without changes in stool or bowel habits. He did not report any constitutional symptoms, lower abdominal pain, weight loss or lumps on defecation. He did not have any previous history of diverticulosis, colonic polyps or chronic liver disease and was not on any medications. He had one second-degree relative diagnosed with colorectal cancer in her seventies. He underwent elective flexible fiberoptic colonoscopy in September 2020 as a Category 1, to be completed within 30 days. The positive endoscopic findings were two colonic polyps in the distal sigmoid: one 12 mm pedunculated polyp and a 30 mm pedunculated bilobed polyp, the lesion of interest (Fig. 1). Both polyps were resected as described in Fig. 1. The second polyp was a pedunculated polyp with a single common stem and bifid, dividing into two stalks halfway before it ends with two separate caps. Both the normal endoscopic view and when viewed using narrowband imaging (NBI) techniques are described in Figs. 1 and 2, respectively. Histopathology of the smaller polyp concluded a tubule-villous adenoma with low-grade dysplasia while the larger bilobed polyp was concluded to be a tubulovillous adenomawith high-grade dysplasia. Repeat colonoscopy in October 2021 was normal without any residual mucosal features. He is asymptomatic to date without any further bleeding. This case report is the second case report of a bilobed colonic polyp published in scientific literature to date, after a literature search conducted by the authors. Initially it was found by Bianchi et al. who was the first to report and coin the name ‘Siamese twins polyps’. Alternatively, multiple bilobed polyps have been reported in the ureters as well as the oesophagus. Similar to the previous case report, the unique features of the bilobed polyp found in our patient includes a pedunculated bifid appearance arising from a common stalk; (Fig. 1). The Paris endoscopic classification was used to classify the polyp as pedunculated according to its macroscopic appearance. However the moderate size of the lesion in addition to the bilobed polyp morphology has not been described in the Paris classification. Theoretically, there is no evidence of malignant risk associated with these kinds of bilobed polyps apart from their size. However, this presents the endoscopist with a degree of uncertainty when attempting to resect the polyp as endoscopists must decide if the endoscopic or macroscopic resection is complete at the time of the polypectomy. The only favourable feature was that it had a long pedunculated appearance. Nevertheless, as shown in Fig. 2, this case study shows that NBI alongside histology confirmed high-grade dysplasia within the polyps. This suggests our bilobed polyp had the potential to progress down the metastatic cascade akin to their more common monolobed cousins. The conundrum faced by even senior endoscopists is whether we treat these lesions similarly to traditional polyps. In our case, the histological features and the Haggitt classification, become very important determinants of the risk of residual disease which was deemed clear of margins in our patient. Another important consideration when examining the histopathology report of our bilobed polyps was whether the dysplasia described by histopathological analysis is the same in each lobe or does each lobe individually exhibit differences in the degree of dysplasia despite sharing a common stalk. Furthermore, in future studies it is important to evaluate the molecular basis of the dysplasia in bilobed polyps compared to conventional monolobar polyps and