Colloid Carcinoma of the Pancreas: A Distinct and Less Aggressive Entity in the Spectrum of Pancreatic Malignancies

Pancreatic colloid carcinoma (CC) is a rare subtype of invasive carcinoma arising from intraductal papillary mucinous neoplasm (IPMN), characterized by abundant extracellular mucin and an intestinal phenotype. Its rarity (1-3% of pancreatic cancers) and inclusion in heterogeneous cohorts have limited a clear definition of its behavior. This study aimed to characterize CC and compare it with IPMN-derived tubular carcinoma (TC).

Patients resected for an IPMN at a single institution (1990-2025) were identified. A subset of 50 CC and 145 TC cases was selected. Demographic, clinical, radiological, pathological, and outcome data were analyzed.

CC accounted for 25% of invasive IPMN. Patients with CC were more often male (70% versus 41%) and had higher rates of steatorrhea (26% versus 3%), diabetes (44% versus 27%), and pancreatitis (36% versus 17%) compared with TC (all p < 0.05). Most tumors arose in the head (64%) and showed high-risk stigmata (94%). Nearly all CC displayed intestinal differentiation and main duct involvement (98% each). Compared with TC, CC was often node-negative (80% versus 57%, p < 0.01), with less perineural (28% versus 58%, p < 0.001) and vascular invasion (6% versus 26%, p = 0.002). CC was associated with significantly longer median overall survival (69 versus 31 months, p = 0.02). Recurrence was uncommon (5-year RFS 58%) and predominantly distant (80%), with distinct patterns including bone metastases (19%) and pseudomyxoma peritonei (8%).

Colloid carcinoma is a distinct subtype of invasive IPMN with indolent behavior. Recognition of its unique features may refine prognostic stratification and guide tailored management.