MR imaging of pituitary hyperplasia in a child with growth arrest and primary hypothyroidism.

Magnetic resonance imaging of pituitary hyperplasia has been rarely described in children with primary hypothyroidism. We report a case of pituitary hyperplasia in a child presented with significant growth arrest and laboratory evidence of hypothyroidism. Magnetic resonance imaging revealed symmetrical pituitary enlargement simulating macroadenoma. After thyroid hormone replacement therapy, the child's height increased and pituitary enlargement regressed to normal. Awareness of MRI appearance of pituitary hyperplasia in children with laboratory evidence of hypothyroidism might avoid misdiagnosis for pituitary tumor, which may also manifest as growth disorder, obviating unnecessary surgery.