Cytopathology of anaplastic carcinoma of the pancreas: Review of a rare entity and description of a variant with signet ring cell features

Anaplastic carcinoma of the pancreas (ACP) is a rare and aggressive variant of pancreatic ductal adenocarcinoma (PDAC). Several studies have attempted to characterize this subtype through case series or single case reports; however, ACP remains underrecognized by cytopathologists in particular, and often lumped under the umbrella of classic PDAC. Here, we review the most up to date data that literature provides about ACP, to bring familiarity with this entity to the cytopathology practice, and to elucidate the role cytopathologists can play in recognizing and diagnosing this subtype on pancreatic aspiration biopsy, before surgical resection. We also describe a rare case of ACP, demonstrating signet ring cell features, that was diagnosed on fine needle aspiration of a pancreatic mass.