The potential of flat-elevated colorectal adenomas to undergo rapid malignant transformation and progression to invasive carcinoma is still under discussion. Therefore, a total of 130 colorectal neoplastic lesions > or = 1 cm in diameter were examined after endoscopic or surgical resection. Lesions were macroscopically classified into three categories: (1) flat elevation (22 lesions), superficially elevated lesion with a smooth surface; (2) granular laterally spreading tumor (GLST; 26 lesions), laterally spreading aggregates of nodules forming a lesion with granular surface, and (3) polypoid (82 lesions), pedunculated, subpedunculated and sessile polyps. The adenomatous component showed a tubulovillous architecture in 9/26 (35%) of GLST and 18/82 (22%) of polypoid lesions, however none of the flat-elevated lesions had a villous component (p <0.01; p <0.05). Carcinoma was present in 17/22 (77%) flat elevations, 37/82 (45%) polypoid lesions and 11/26 (42%) GLST (p <0.05). None of the carcinomas arising in GLST and only 1/37 (3%) of those developing in polypoid lesions were invasive carcinomas, but 4/17 (24%) carcinomas arising in flat elevations showed submucosal invasion. Moreover, while all 5 noncancerous flat elevations showed severe atypia, 17/82 (21%) polypoid lesions and 5/26 (19%) GLST showed moderate atypia. In conclusion, flat-elevated colorectal neoplasms have a high malignant potential and the role of these lesions as precursors of colorectal carcinomas deserves greater emphasis.
No takes yet. Share an insight, caveat, or question.
Teixeira et al. (2009) studied this question.