Crystal Violet Staining for Colitis-associated Neoplasia-guided Delineation of Ulcerative Colitis-associated Neoplasia for Endoscopic Submucosal Dissection: A Four-case Report.

Ulcerative colitis-associated neoplasia (UCAN) is often difficult to delineate because chronic inflammatory changes obscure lesion borders. Accurate assessment of lesion extent is essential for curative endoscopic submucosal dissection (ESD), yet conventional white-light imaging frequently fails to clearly define lateral tumor spread. We report four patients with UCAN in whom crystal violet staining for colitis-associated neoplasia (CV-SCAN) was used to delineate lesion extent before ESD. All patients had ulcerative colitis in clinical remission and underwent surveillance colonoscopy. In these four patients, UCAN was identified as CV-neoplasia (CV-N) areas during CV-SCAN, whereas lesion borders remained indistinct on conventional white-light imaging. After histological confirmation by targeted biopsy, a repeat CV-SCAN was performed to determine lesion extent before ESD. In three patients, the CV-N-positive areas corresponded well with the pathological extent of neoplasia, and en bloc curative resection was achieved. One patient had a positive horizontal margin after the initial ESD. During an additional procedure, residual UCAN was again visualized as a CV-N-positive area and was successfully removed by additional ESD. No procedure-related adverse events or local recurrences were observed during follow-up. These cases suggest that CV-SCAN may facilitate delineation of UCAN before ESD and may help identify residual neoplasia that is difficult to recognize using white-light imaging alone. CV-SCAN should be considered an adjunctive technique that complements conventional endoscopic modalities rather than a standalone approach for lesion delineation.