We report a case of a 39–year–old male who visited our hospital due to painful oral ulcers for 6 months. Under the impression of pemphigus, he received steroid therapy. A malignancy survey disclosed a retroperitoneal mass of about 7 cm in diameter over the left suprarenal space. Angiograghy
showed a hypervascular lesion with blood supply from adrenal vessels. Surgical excision was carried out, and histopathological examination confirmed a diagnosis of the hyaline type of Castleman disease. The postoperative course was smooth, and he was discharged 9 days after
the operation. The patient has been followed up for 6 months without local recurrence.