# Pancreatic Head Cancer Masquerading as Distal Cholangiocarcinoma: Diagnostic Challenges, Tumor Characteristics, and Oncologic Outcomes

## TL;DR

This study shows that some pancreatic cancers initially mistaken for bile duct cancer have better survival rates, suggesting they may be a less aggressive type.

## Contribution

The study identifies a potentially less aggressive subtype of pancreatic cancer that mimics distal cholangiocarcinoma.

## Key findings

- Patients with pancreatic cancer misdiagnosed as bile duct cancer had survival rates comparable to typical pancreatic cancer cases.
- These misdiagnosed pancreatic cancers were associated with better overall survival in multivariable analysis.
- The findings suggest a need for improved diagnostic methods to distinguish these cancers preoperatively.

## Abstract

Accurately distinguishing between pancreatic head cancer and distal cholangiocarcinoma before surgery is difficult because they occur in the same area and share similar symptoms. This distinction is critical because treatment plans differ, especially regarding the use of neoadjuvant chemotherapy before surgery. Our study analyzed patients who were initially thought to have distal cholangiocarcinoma but were later diagnosed with pancreatic head cancer after surgery. We found that although these cases often required more complex surgery, the patients had comparatively better survival outcomes than those typical for pancreatic head cancer. This suggests that pancreatic cancers that mimic distal cholangiocarcinoma might be a biologically less aggressive subtype. These findings highlight the need for better diagnostic methods to ensure each patient receives the most effective treatment plan from the start, potentially improving survival for this specific group.

Background/Objectives: Differentiating pancreatic head cancer (PHC) from distal cholangiocarcinoma (dCCA) remains clinically challenging and directly influences treatment strategy. This study evaluates the clinicopathologic features and outcomes of patients with PHC who were preoperatively designated as dCCA. Methods: We retrospectively analyzed patients undergoing pancreatoduodenectomy for suspected dCCA or PHC from 2019 to 2023. Patients were stratified by pre- and postoperative diagnoses into three groups: confirmed dCCA (B-B), confirmed PHC (P-P), and dCCA reclassified as PHC (B-P). Clinicopathologic features, perioperative outcomes, and survival were compared. Results: This analysis included 159 patients, B-B = 31, P-P = 115, and B-P = 13. Despite a more advanced stage, a lower R0 rate (p = 0.043), and unplanned portal vein resection confined to B-P (p < 0.001), overall and recurrence-free survival were comparable to P-P (p = 0.363 and 0.183). In multivariable Cox analysis, B-P remained an independent favorable prognostic factor for overall survival (Hazard ratio 0.137, p = 0.020). Conclusions: Approximately one-third of cases initially diagnosed as dCCA were ultimately PHC. These PHC cases mimicking dCCA demonstrated comparable or even superior survival, suggesting a biologically indolent subset. Refinement of diagnostic criteria and integrated clinicopathologic assessment are essential for optimizing preoperative management strategies.