Perivesical unicentric Castleman disease initially suspected to be metastatic prostate cancer

Unicentric Castleman disease (UCD) is a relatively rare lymphoproliferative disease, which commonly presents as a mediastinal mass and less frequently involves abdomen, pelvis, and retroperitoneum. We report a case of a 64-year-old man with newly diagnosed low-volume, Gleason 3 + 3 = 6 prostate adenocarcinoma, who in considering active surveillance versus treatment was found to have a left perivesical and iliac chain lymphadenopathy concerning for potential metastatic involvement. He underwent magnetic resonance imaging with ferumoxytol to assist in the diagnostic evaluation to better characterize his lymphadenopathy. Subsequently, he underwent robotic-assisted laparoscopic bilateral pelvic lymph node dissection and resection of left perivesical mass exhibiting hyaline vascular variant of UCD.