BACKGROUND Castleman's disease (CD) is an angio-follicular lymph node hyperplasia presenting as a localized or a systemic disease masquerading malignancy. The most common sites of CD are mediastinum, neck, axilla and pelvis. Unicentric CD in the peripancreatic region is very rare. METHODS We report a case of the 34-year-old lady presenting with epigastric pain for 3 months. Abdominal imaging revealed a retroperitoneal mass arising from the pancreas suspected to be neuroendocrine tumor. Tumor markers were not elevated. Complete surgical excision was performed and patient had uneventful recovery. Pathologic findings demonstrated localized hyaline-vascular type of Castleman's disease. CONCLUSIONS CD is a very rare cause for development of retroperitoneal mass. It is more frequent in young adults without predilection of sex. It can occur anywhere along the lymphoid chain. Abdominal and retroperitoneal locations usually present with symptoms due to the mass effect on adjacent organs. CD appears as a homogeneously hypoechoic mass on ultrasound and non-specific enhancing homogeneous mass with micro calcifications on computed tomography. Histologically, the hyaline vascular type demonstrates a follicular and inter-follicular capillary proliferation with peri-vascular hyalinization, with expansion of the mantle zones by a mixed inflammatory infiltrate of numerous small lymphocytes and plasma cells. The standard therapy of localized form is en bloc surgical excision as performed in our case. CONCLUSIONS Unicentric CD in the peripancreatic region is difficult to differentiate from pancreatic neoplasm preoperatively. However, preoperative biopsy in cases of high clinical suspicion can help in avoiding extensive surgery for this benign disease.