Colorectal Cases

Overall Comment

This case demonstrates an 11-mm rectal lesion (Rb) of macroscopic type 0-IIa+IIc, showing a superficially elevated component with a central depressed area and peripheral whitish change. On NBI, the depressed surface was clearly recognized, and closer observation revealed irregular vascular architecture and irregular surface pattern, leading to an optical diagnosis of JNET Type 2B. NBI-TXI made these abnormalities even more conspicuous. Magnifying NBI showed that the JNET Type 2B area extended over at least 3 mm, while magnifying NBI-TXI demonstrated white opaque substance (WOS), a finding characteristic of carcinoma. Indigo carmine chromoendoscopy further highlighted the irregular surface morphology, and crystal violet chromoendoscopy revealed a severely irregular Kudo type VI pit pattern with a positive invasive pattern, strongly suggesting SM2 or deeper submucosal invasion. Based on these findings, PAEM (peranal endoscopic myectomy) was performed. Histopathology confirmed adenocarcinoma (tub1+tub2), pT1b (SM1506 μm), BD1, ly0, v0, pHM0, pVM0. After discussion with the patient, the lesion has been managed with follow-up, and no recurrence has been observed. This highly educational case highlights the importance of integrating morphology, vascular and surface pattern analysis, WOS, and pit pattern assessment for accurate invasion-depth diagnosis in small rectal lesions.