Metastatic neoplasms to the pancreas diagnosed by fine-needle aspiration/biopsy cytology: A 15-year retrospective analysis.

BACKGROUND: Metastatic tumors to the pancreas are rarely encountered and diagnostically challenging. We aspired to determine the incidence and origin of all metastases to the pancreas at our institution, and to examine their clinicopathologic and cytomorphologic features. We also sought to ascertain the effect of endoscopic ultrasound (EUS) guidance implementation.

METHODS: A search of our database was undertaken to review all pancreatic FNA and/or CNB examined from January 2000 through December 2014.

RESULTS: During our 15-year study, 636 patients underwent pancreatic FNA/CNB, including 252 (40%) computerized tomography (CT) and 384 (60%) EUS-guided biopsies. Malignancy was diagnosed in 221 (35%). Only 16 had metastases to the pancreas, comprising 2.5% of pancreatic biopsies and 7.2% of malignancies. Three (18.8%) presented with their first manifestation of cancer. EUS guidance was utilized in 50%, with rapid on-site evaluation (ROSE) employed in 14 (88%). The most common primary site was lung (6,38%), followed by 3 (19%) each of renal and gastrointestinal malignancies. The remaining included malignant melanoma, Merkel and gallbladder small cell carcinomas, and olfactory neuroblastoma.

CONCLUSION: Cytologic diagnosis of metastasis to the pancreas is rare in our institution, comprising only 2.5% and 7.2% of total and malignant pancreatic FNA/CNB, respectively. FNA/CNB with ROSE proved to be an effective diagnostic modality, thereby obviating the need for more invasive procedures in the setting of pancreatic metastases. EUS-FNA was equally effective as CT-guided biopsies in achieving specimen adequacy and definitive diagnoses. We also present the first known case of a metastatic olfactory neuroblastoma to the pancreas diagnosed by imprint cytology.