Castleman disease is an uncommon lymphoproliferative disorder that usually presents asymptomatically at a single site, most commonly the mediastinum; it is rare in the head and neck. Although Castleman disease may be mistaken for a malignant process such as lymphoma, it is a benign condition that is curable with complete surgical resection. We report the case of a 43-year-old man with the hyaline vascular type of unicentric Castleman disease who presented with an isolated neck mass.