Microfollicular thyroid adenoma and congenital goitrous hypothyroidism.

Three patients with congenital goitrous hypothyroidism are reported. They were treated with adequate thyroxine replacement and developed well defined microfollicular thyroid adenomas despite being euthyroid clinically and biochemically throughout their clinical course. Patients with congenital goitrous hypothyroidism appear to be at increased risk of developing thyroid adenoma in childhood despite the use of replacement thyroxine treatment in physiological doses.