From the Guidelines
The next step in the workup for a mass with metastatic pancreatic source despite normal CT findings should be endoscopic ultrasound (EUS) with fine needle aspiration (FNA). EUS is more sensitive than CT for detecting small pancreatic lesions, particularly those less than 2 cm, and allows for tissue sampling through FNA to confirm the diagnosis 1. This should be followed by comprehensive staging with additional imaging such as MRI with MRCP (magnetic resonance cholangiopancreatography) to better visualize the pancreatic and biliary ducts, and possibly PET-CT to identify distant metastases that may have been missed on conventional CT.
Some key points to consider in the workup and staging of pancreatic cancer include:
- The use of CA 19-9 as a tumor marker, which can be useful in guiding treatment decisions and measuring disease burden, but has limited diagnostic value due to its lack of specificity and potential for false-positive results in cases of cholestasis 1.
- The importance of assessing vascular invasion and predicting resectability, for which EUS has been shown to be valuable 1.
- The role of MRI and MRCP in solving problems such as detecting hepatic lesions that cannot be characterized by CT, and in evaluating biliary anatomy and cystic neoplasms of the pancreas 1.
Laboratory tests including CA 19-9 tumor marker, liver function tests, and baseline nutritional parameters should be obtained. A multidisciplinary tumor board discussion is essential to determine the best treatment approach based on the extent of disease. The combination of these diagnostic modalities provides complementary information when CT findings are normal despite evidence of metastatic disease, as pancreatic cancer can sometimes present with metastases before the primary tumor is radiologically apparent due to its aggressive nature and tendency for early dissemination.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Next Steps in Workup for Mass with Metastatic Pancreas Source and Normal CT Findings
- In cases where a mass is suspected to have a metastatic pancreas source but CT findings are normal, further diagnostic steps are necessary to confirm the diagnosis and determine the primary source of the metastasis.
- According to 2, endoscopic ultrasound (EUS)-fine needle aspiration (FNA) can be a feasible way to make an accurate histopathological and definitive diagnosis of metastatic disease to the pancreas.
- The use of EUS-FNA has been shown to be effective in diagnosing metastatic disease to the pancreas, with a study by 2 reporting that 10% of solid pancreatic masses were found to be metastatic in origin.
- In addition to EUS-FNA, other imaging modalities such as MRI may also be useful in detecting pancreatic metastases, as reported by 3.
- CT-guided biopsy may also be performed to obtain a definitive tissue diagnosis, as described in 3.
- Immunohistochemical staining can also play a role in diagnosing metastatic disease to the pancreas, as shown in 4, where staining for cytokeratin 7, TTF1, chromogranin A, and synaptophysin helped to confirm the diagnosis of metastatic small-cell carcinoma.
Considerations for Diagnostic Approach
- The choice of diagnostic approach may depend on the suspected primary source of the metastasis, as well as the patient's overall clinical presentation and medical history.
- A study by 5 reported that metastases to the pancreas can have a variety of appearances on CT, including large solitary masses, multinodular lesions, and diffuse enlargement of the pancreas.
- The study by 5 also highlighted the importance of considering the primary source of the metastasis when interpreting imaging findings, as the appearance of the metastasis can sometimes resemble that of the primary tumor.
- In cases where the primary source of the metastasis is unknown, a thorough diagnostic workup, including imaging and biopsy, may be necessary to determine the origin of the metastasis.