Metastases to the pancreas diagnosed by fine-needle aspiration

Background: Metastatic cancer infrequently involves the pancreas. When the pancreas hosts a metastatic tumor, cytopathological evaluation of fine-needle aspirate material is a crucial part of the diagnostic process. In this study, we show two institutions' experience with cytopathological diagnosis of pancreatic metastasis. Methods: Databases of institutional experience at The Johns Hopkins Hospital and Ohio State University Medical Center were queried for cases of metastatic tumors in the pancreas that underwent fine-needle aspiration. Demographic and pathological features were compiled and the cytomorphology was reviewed. Results: Forty-two cases of tumor metastasis to the pancreas were found. Over the time of this review, 5,495 aspirates were performed, and 43% (2,389/5,495) had malignant cytological findings. Thus, the 42 cases of metastatic disease to the pancreas comprised 0.8% of all pancreas aspirates and 1.8% of the malignant ones. Renal cell carcinoma was the most common metastasis, followed by melanoma and non-small cell lung carcinoma. Among the other tumors in this series, 2 cases each of rare metastases such as the fibrolamellar variant of hepatocellular carcinoma and solitary fibrous tumor were also seen. Conclusion: The pancreas is rarely involved with metastatic disease, but when it is involved the most common tumor is renal cell carcinoma followed by melanoma and non-small cell lung cancer. Clinical history and awareness of the primary pancreatic mimickers are necessary for arriving at the correct diagnosis. As conventional pancreatic adenocarcinoma is uncommon in children and young adults, history of other tumors-even ones that usually follow an indolent course-is essential.