Castleman's disease arising from the gallbladder neck causing difficulty in the differential diagnosis.

We report a patient with Castleman's disease arising from the gallbladder neck, which caused difficulty in making the differential diagnosis against gallbladder malignancies. A 50-year-old woman presented to our institution with epigastric pain. An abdominal computed tomography scan (CT) and magnetic resonance cholangiopancreatography (MRCP) study showed a 20-mm tumor located in the gallbladder neck for which malignancy could not be completely ruled out. For the definitive diagnosis and treatment, cholecystectomy was performed. In the operation, the main tumor and resection margins of the cystic duct were submitted for frozen section. The tumor was composed of a proliferation of lymphoid tissue with no signs of dysplasia. The ductal margin was free of tumor. The final histopathological diagnosis was unicentric Castleman's disease, a hyaline vascular variant that developed in the gallbladder. The patient is currently in good condition without any signs of recurrence 28 months after the operation. This is the first detailed report of Castleman's disease of the gallbladder. Making a correct diagnosis was very difficult before the operation, and only a surgical approach enabled confirmation of the diagnosis for this patient.