Abstract
Background Biliary cystic neoplasms (BCNs), comprising biliary cystadenomas (BCAs) and cystadenocarcinomas (BCACs), are rare cyst-forming epithelial tumours of the liver and biliary tract. Differentiation between benign and malignant lesions remains challenging preoperatively, and current imaging criteria lack sufficient discriminatory power. This study aimed to correlate preoperative imaging features with final histology to better identify radiologic markers of malignancy in BCN. Methodology A retrospective analysis was conducted on 42 histologically confirmed cases of BCAs or BCACs discussed at a specialist hepatopancreatobiliary multidisciplinary team between 2010 and 2023. All cases had preoperative cross-sectional imaging (CT and/or MRI or magnetic resonance cholangiopancreatography). Imaging studies were reviewed for features including wall enhancement, septations, mural nodules, calcification, and internal fluid complexity. Histology was categorised into low-grade dysplasia (LGD), high-grade dysplasia (HGD), or invasive carcinoma (BCAC). Results Of the 42 cases, 39 (93%) were LGD BCA, two (5%) were HGD BCA, and one (2%) was BCAC. Wall enhancement was significantly more common in advanced histology (67%) compared to LGD (28%), and thick fluid density also correlated with advanced pathology (33% vs. 8%). Mural nodules were present only in LGD cases (10%) and absent in HGD or BCAC. The sensitivity and specificity of wall enhancement for advanced histology were 67% and 72%, respectively. Notably, ovarian-type stroma (OTS), a diagnostic criterion in the WHO 2022 classification, was absent in 24% of cases, yet these were still reported as BCAs based on traditional morphological features. Conclusions Wall enhancement and complex fluid characteristics are the most suggestive imaging features of advanced BCN; however, significant overlap with benign lesions limits their diagnostic accuracy. Mural nodules were not predictive of malignancy in this cohort. Our findings support surgical resection of all complex or atypical cystic liver lesions and highlight the variability in real-world histopathological classification, especially regarding OTS. Multidisciplinary consensus and histologic evaluation remain critical for definitive diagnosis.