Follicular Pancreatitis: A Case Report

Follicular pancreatitis (FP) is a rare form of localized pancreatitis that can easily be confused with a pancreatic tumor. This article reports a case of FP, including its clinical presentation, radiological features, and pathological findings. A 50-year-old male presented to our hospital with a one-month history of abdominal pain. Abdominal contrast-enhanced CT and abdominal contrast-enhanced MRI revealed a mass in the tail of the pancreas with local encasement of the splenic vein and significant narrowing, raising suspicion of pancreatic cancer. PET-CT revealed a slightly low-density lesion measuring 5.3×4.9 cm in the tail of the pancreas with abnormally increased FDG uptake and an SUV max of 5.9, suggesting a malignant lesion. The surgical team performed robotic distal pancreatectomy with splenectomy. Postoperative pathology revealed severe chronic inflammation in the pancreatic tissue, with numerous lymphoid follicles and lymphoplasmacytic infiltrates around the ducts and in the interstitium. Immunohistochemical staining revealed IgG4/IgG<10%, indicating a diagnosis of follicular pancreatitis. The patient was discharged 11 days after surgery. Apart from a grade B pancreatic fistula, there were no other surgical complications. FP is a rare type of chronic pancreatitis characterized by intrapancreatic lymphoid follicles with reactive germinal centers. It is difficult to differentiate this disease from pancreatic cancer. In clinical practice, EUS-FNA should be performed for patients suspected of having FP, and a diagnosis should be made with a multidisciplinary approach, including serology, imaging, and histopathology, to minimize unnecessary surgery.