A Cystic Variant of Acinar Cell Carcinoma of the Pancreas with Repeated Bleeding from a Pseudoaneurysm: A Case Report.

introductionAcinar cell carcinomas are rare pancreatic neoplasms, accounting for approximately 1% of all exocrine pancreatic tumors. We describe a case of a cystic variant with intracystic hemorrhaging that was difficult to differentiate from a pseudocyst due to its morphology. CASE PRESENTATION: A 54-year-old man was admitted with severe left upper quadrant abdominal pain. Imaging studies showed a 7.0-cm internal heterogeneous cystic lesion with a splenic artery pseudoaneurysm near the lesion. Transarterial embolization of the splenic artery was performed, but rebleeding occurred 1 month later. Distal pancreatectomy with partial resection of the stomach revealed internal nodular lesions on the resected specimen. Microscopically, the cystic mass was composed of neoplastic tissue with papillary and tubular structures. The tumor was diagnosed as acinar cell carcinoma since immunohistochemical examination showed tumor cells positive for BCL10, lipase, and trypsin. The patient experienced local recurrence 6 months postoperatively, received chemotherapy with gemcitabine followed by S-1, underwent a 2nd resection at 18 months, and has remained recurrence-free for 15 years.

conclusionsAcinar cell carcinoma rarely presents with a cystic structure and may be accompanied by a pseudoaneurysm, which can complicate differentiation from a pancreatic pseudocyst, highlighting the importance of careful differential diagnosis for appropriate treatment.