Lymph node metastatic status could predict the prognosis of intracholecystic papillary neoplasm of gallbladder.

Intracholecystic papillary neoplasm (ICPN) is a non-invasive epithelial tumor that presents as a grossly identifiable mass arising in the mucosa and protruding into the lumen. ICPN is associated with invasive carcinoma. There are few studies on the clinicopathological features of ICPN, including that with invasive carcinoma. We evaluated the clinicopathological characteristics of 42 ICPNs and 41 conventional gallbladder adenocarcinomas (cGBAs). Subserosa or deeper (≥ss) invasion was significantly lower in ICPN (61.9%) than that in cGBA (90.2%) (P = 0.004). Cox regression analysis revealed that lymph node metastasis (hazard ratio [HR] [95% confidence interval (CI)]: 2.610 [1.131, 6.024], P = 0.025) and positive margin (HR [95% CI]: 5.143 [2.113, 12.516], P < 0.001), but not ≥ss invasion (HR [95% CI]: 1.541 [0.479, 4.959], P = 0.469), were independent prognostic factors. In addition, there was a significant interaction between histological type and lymph node metastasis (HR [95% CI]: 0.191 [0.042, 0.983], P = 0.033). In cGBA, the presence or absence of lymph node metastasis did not affect prognosis; however, ICPN without lymph node metastasis had better prognosis. Therefore, the histological classification of ICPN and cGBA and the pathological evaluation of lymph node metastasis in ICPN are crucial for determining prognosis.