Pancreatic Amphicrine Carcinoma With Acinar and Neuroendocrine Differentiation: A Comprehensive Case With Radiological, Cytopathological and Ultrastructural Findings, and Literature Review.

Amphicrine carcinoma is a rare malignancy exhibiting dual differentiation toward both exocrine and endocrine lineages within the same tumor cells. We report a case of pancreatic amphicrine carcinoma with acinar and neuroendocrine differentiation in an elderly man (85 years old at surgery). An 8-mm nodule in the pancreatic body was detected by abdominal ultrasonography. Magnetic resonance imaging revealed a high-signal nodule on diffusion-weighted imaging but indistinct findings on T1- and T2-weighted images, and the lesion was also indistinct on dynamic contrast-enhanced computed tomography. Endoscopic ultrasonography (EUS) clearly visualized the lesion, and EUS-guided fine-needle aspiration revealed malignant cells with acinar-like structures and granular cytoplasm. Distal pancreatectomy was subsequently performed, and the tumor was pathologically diagnosed as amphicrine carcinoma. Dual differentiation toward acinar and neuroendocrine lineages was confirmed by immunohistochemistry and ultrastructural examination. To our knowledge, this is the first report to comprehensively describe a pancreatic acinar-type amphicrine carcinoma, including radiological, cytopathological, and ultrastructural findings. The present case highlights the diagnostic value of multimodal imaging and cytopathological evaluation and may serve as a reference for diagnosing such rare tumors. It may also offer new insights into the future classification of pancreatic amphicrine and amphicrine-like tumors within a similar biological spectrum.