SECONDARY hyperparathyroidism associated with chronic renal disease may simulate primary hyper-parathyroidism with secondary renal impairment in virtually every particular. An exception is the brown tumor, a relatively rare lesion, which has been considered to be almost specific for primary hyperpara-thyroidism and which to our knowledge has not previously been described as a manifestation of secondary parathyroid hyperplasia. Case Report A 22-year-old man was found to be hypertensive during a college entrance examination in January, 1962. He was asymptomatic. The past medical history revealed an operation for bladder-neck obstruction at the age of 3, but he had apparently been well since . . .