Serous cystadenoma with fat replacement of the pancreatic body and tail with pancreaticoduodenectomy without pancreatic reconstruction followed by preserved pancreatic endocrine function.

Acquired fat replacement of the pancreatic body and tail is a rare condition that differs from congenital agenesis. A female patient in her 50s presented with a multilocular serous cystic neoplasm located in the pancreatic head extending into the body, accompanied by fat replacement in the pancreatic body and tail. The patient underwent pancreaticoduodenectomy (PD) without remnant pancreatic reconstruction, as the pancreatic duct could not be identified. Postoperatively, no complications occurred, including pancreatic fistula, and endocrine function remained intact, with no diabetes treatment required at the 1-year follow-up. Histopathology confirmed the diagnosis of serous cystadenoma with preserved Langerhans islets within the fat-replaced pancreatic tissue. This case emphasises the potential of preserving endocrine function and preventing complications through PD without reconstruction in cases involving extensive fat replacement.