Undifferentiated pancreatic cancer with osteoclast-like giant cells: imaging features

The 2019 WHO classification of pancreatic ductal adenocarcinoma (PDAC) recognizes undifferentiated carcinoma with osteoclast-like giant cells (UCOG) as a rare subset. There is sparse literature on the imaging appearances of this type of cancer. Pathologists also increasingly recognize that poorly-differentiated PDAC may occasionally contain osteoclast-like giant cells (PDO). This study aims to compare the imaging features and natural history of these two groups.

In this retrospective case-controlled study, we searched the Institutional pathology and imaging databases for "pancreas cancer" and "osteoclasts." Of the 59 subjects identified, preoperative imaging (CT or MRI) and acceptable pathology data were available in 25 patients who formed the final study cohort. Two specialist abdominal radiologists independently reviewed the imaging findings. The cohort included 10 patients with PDO and 15 with UCOG.

There were no differences in age or gender between these groups. On logistic regression analysis, only the presence of tumor hemorrhage (p=0.007), and pancreatic duct obstruction (p=0.02) were significantly different between the groups. UCOG had fewer metastases at presentation and follow-up, though the differences were not significant. UCOG had significantly higher overall survival (median 35.4 months vs. 10.7 months, p=0.007) and progression-free survival (median 33.0 months vs. 9.1 months, p=0.003), compared to PDO.

The presence of a large (>6 cm) solid pancreatic mass that shows hemorrhage, exophytic growth, and lack of pancreatic duct obstruction may raise the possibility of UCOG. Despite larger size at presentation, these tumors generally have a better prognosis than the published prognosis for conventional PDAC.