[EXTRAMEDULLARY HEMATOPOIESIS PRESENTING AS A RENAL MASS DURING TREATMENT OF CASTLEMAN DISEASE : A CASE REPORT]

A 66-year-old man receiving medication for Castleman disease was found to have a gradually enlarging renal mass on a computed tomography (CT) scan. Contrast-enhanced CT and magnetic resonance imaging scan were performed for diagnostic evaluation, and renal cell carcinoma was suspected, prompting consideration of surgical resection. However, we determined that histopathological confirmation was necessary to rule out recurrent Castleman disease and other conditions. Therefore, we performed a tumor biopsy before any surgical intervention. An ultrasound-guided percutaneous needle biopsy revealed extramedullary hematopoiesis. Currently, the lesion is under observation without intervention.