Castleman Disease Mimicking Pancreatic Neuroendocrine Tumour: Interpretation of Positron Emission Tomography in Pancreatic Incidentaloma

We report a rare case of an incidental pancreatic lesion that proved to be Castleman disease in a peripancreatic lymph node, which mimicked a high-grade pancreatic neuroendocrine tumour (PNET) based on findings on positron emission tomography (PET). The disease was discovered as an incidental finding on CT imaging of the abdomen and was investigated and managed as PNET. Surgical resection was performed with distal pancreatectomy and splenectomy, however, histology revealed the lesion was a lymph node affected by Castleman disease. Often termed the great mimic, Castleman disease is a rare lymphoproliferative disorder that is often mistaken for other primary lesions of the organ due to its location and should be considered a differential of fluorodeoxyglucose (FDG)-avid PET lesions on imaging.