Castleman disease is a rare and benign disorder, characterized by enlarged lymph nodes and angiofollicular lymphoid hyperplasia. We report a case of a 57-year-old male, who was admitted to our surgical department because of a retroperitoneal nodular mass measuring about 4 cm in maximum diameter, incidentally discovered on a radiologic exam performed for the onset of vague abdominal pain with posterior irradiation. The patient was subdue to laparoscopic removal of the mass and no intra- and post-operative complications were recorded. Histologic diagnosis of hyaline-vascular variant of the Castleman disease was confirmed. Only two cases have been found in the literature reporting the paraduodenal unicentric Castleman disease localization like our case. Although rare, the Castleman disease must be considered in the differential diagnosis among all the lymph nodes diseases, for avoiding improper therapies.