Multinodular cystic pancreatic acinar cell carcinoma presenting as a splenic hilum cyst with peritoneal carcinomatosis: a case report.

Pancreatic acinar cell carcinoma (PACC) is a rare malignancy accounting for 0.2%-4.3% of pancreatic tumours, typically affecting older men. Cystic variants are exceptionally uncommon and often mimic benign pancreatic lesions, posing diagnostic challenges. We report a 37-year-old woman who was incidentally found to have a large multiseptated lesion involving the pancreas, spleen, and retroperitoneal structures. Surgical exploration demonstrated multiple peritoneal and hepatic nodules. Distal pancreatectomy, splenectomy, omentectomy, and resection of hepatic lesions were performed. Histopathology confirmed poorly differentiated pancreatic acinar cell carcinoma with extensive peritoneal metastases. Postoperative recovery was uneventful. This case highlights a rare cystic presentation of PACC in an atypical demographic. Clinicians should maintain a high index of suspicion for rare pancreatic malignancies in the differential diagnosis of complex cystic abdominal lesions.