Hyperplasia of adrenal rest tissue causing a retroperitoneal mass in a child with 11 beta-hydroxylase deficiency

We report the case of a child with congenital adrenal hyperplasia due to 11β-hydroxylase deficiency, with hyperplasia of adrenal rest tissue presenting as a retroperitoneal mass. Complete resolution of the mass was noted after 18 months of hydrocortisone replacement therapy.