Recurrent hypertensive cerebral hemorrhages in a boy caused by a reninoma: rare manifestations and distinctive electron microscopy findings.

Recurrent cerebral hemorrhages caused by hypertension secondary to reninoma are extremely rare in children. Because of its detrimental effects on children's health, the importance of early diagnosis of and treatment for reninoma should be emphasized. Here, the authors present a 10-year-old boy with intermittent headaches and neurologic deficiency symptoms caused by hypertension. A reninoma in the right kidney was detected and successfully treated with laparoscopic partial nephrectomy. Two cell types were revealed in the tumor tissue under electron microscopy: renin secreting tumor cells and mast cells. This rare case expands our knowledge of hypertension in children and provides direct evidence that mast cells may infiltrate reninoma.