What's the next step in managing a 0.9cm enhancing lesion in the pancreatic head in a 61-year-old female with a history of gastric cancer, status post partial gastrectomy, with a recent Computed Tomography (CT) abdomen/pelvis and Positron Emission Tomography/Computed Tomography (PET/CT) showing no increased Fluorodeoxyglucose (FDG) uptake?

Management of a 0.9cm Pancreatic Head Lesion in a Patient with History of Gastric Cancer

The next step in managing this 0.9cm enhancing pancreatic head lesion should be an endoscopic ultrasound (EUS) with fine needle aspiration (FNA) to establish a definitive diagnosis.

Rationale for EUS-FNA Approach

The 0.9cm enhancing lesion in the pancreatic head presents a diagnostic challenge, particularly given the patient's history of gastric cancer. While the lesion does not demonstrate increased FDG uptake on PET/CT, this finding alone cannot rule out malignancy.

According to ESMO-ESDO clinical practice guidelines 1:

• EUS is the preferred method to complement staging by providing information on vessel invasion and potential lymph node involvement
• EUS is the preferred means to obtain a biopsy of pancreatic lesions when imaging results are ambiguous
• Percutaneous sampling should be avoided due to risk of tumor seeding

The lack of FDG uptake on PET/CT is notable but not definitive, as the ESMO guidelines specifically state that "PET scan is currently not routinely recommended for the staging of ductal pancreatic cancer" 1.

Diagnostic Algorithm

1. EUS-FNA of the pancreatic head lesion

   • Provides tissue diagnosis
   • Allows assessment of local invasion
   • Minimizes risk of tumor seeding compared to percutaneous approaches

2. Based on EUS-FNA results:

   • If malignant pancreatic adenocarcinoma: Consider surgical resection if resectable
   • If neuroendocrine tumor: Management depends on functionality and grade
   • If metastasis from gastric cancer: Consider systemic therapy
   • If benign: Consider surveillance

Surgical Considerations

If the lesion proves to be a primary pancreatic malignancy and is deemed resectable:

• For pancreatic head tumors, pancreatoduodenectomy (Whipple procedure) is the treatment of choice 1
• The goal of surgery is to achieve an R0 resection (margin-negative) 1
• Meticulous perivascular dissection is essential to maximize the chance of complete resection 1

If the lesion is a small (< 2cm) neuroendocrine tumor:

• Enucleation or local excision with peripancreatic lymph dissection may be considered 1

Important Caveats

• Prior gastric cancer history is significant: The lesion could represent metastatic disease from the previous gastric cancer, particularly given the patient's partial gastrectomy status
• Size matters: At 0.9cm, this is a small lesion that may be amenable to less extensive surgery if proven to be a primary pancreatic neoplasm
• Negative PET/CT does not exclude malignancy: Some pancreatic tumors, particularly well-differentiated neuroendocrine tumors, may not show FDG avidity
• Avoid percutaneous biopsy: This approach carries risk of tumor seeding and should be avoided in potentially resectable pancreatic lesions 1

Follow-up Recommendations

After EUS-FNA and definitive diagnosis:

• If malignant and resectable: Proceed with appropriate surgical intervention
• If malignant and unresectable: Consider neoadjuvant therapy or palliative options
• If benign: Consider surveillance with repeat imaging in 3-6 months

This approach prioritizes obtaining an accurate diagnosis while minimizing procedural risks, allowing for appropriate treatment planning based on the specific pathology identified.