Comparative analysis of the CT and MRI features of pancreatic colloid carcinoma

Abstract

To investigate the CT and MRI features of pancreatic colloid carcinoma (PCC) and to correlate imaging findings with histopathological characteristics. The CT and MRI images and clinical data of 15 patients with PCC confirmed by surgical resection and histopathological examination from August 2009 to October 2023 were retrospectively analyzed. All 15 PCC lesions presented as single masses, occurring in 8 males and 7 females (mean age 66 ± 8.4 years). The majority of lesions (73%) were located in the pancreatic head (11 cases), with 2 cases in the body, 1 in the tail, and 1 involving both body and tail. PCC typically manifested as cystic-solid masses with internal septations and calcification (8 cases, 53.3%). Associated findings included pancreatic ductal dilatation (13 cases), pancreatic atrophy (13 cases), and biliary dilatation (12 cases). On dynamic contrast-enhanced imaging, lesions demonstrated mild enhancement in the arterial phase and progressive sponge-like or reticular enhancement in the delayed phase. Compared with the surrounding parenchyma, the degree of enhancement in the arterial phase and portal venous phase was significantly lower (8.2 ± 6.7 vs. 19.3 ± 13.6, 9.67 ± 8.93 vs. 28.3 ± 17.2 HU, respectively; P < 0.05). The apparent diffusion coefficient (ADC) values showed no significant difference between PCC lesions and surrounding parenchyma (2.248 ± 0.454 × 10⁻³ mm²/s vs. 1.829 ± 0.514 × 10⁻³ mm²/s; P > 0.05). Pathologically, all tumors were characterized by neoplastic epithelium suspended in extracellular mucin pools comprising more than 80% of the tumor volume, meeting current WHO diagnostic criteria for PCC. The combination of imaging features in PCC—including presentation as a cystic or cystic-solid mass with progressive delayed sponge-like or reticular enhancement, a salt-and-pepper appearance on T2-weighted images, and frequent calcification—may facilitate its differentiation from other pancreatic cystic neoplasms when considered together. Progressive delayed reticular enhancement reflects fibrous stroma segregating the mucin pools, as confirmed by histopathological correlation.