Germline PRKAR1A, MEN1, AIP, DICER1, CDKN1B, and somatic GNAS mutations were negative. A pituitary biopsy showed hyperplastic pituitary tissue with enlarged cords of GH and prolactin cells. Magnetic resonance imaging demonstrated a homogenous bulky pituitary gland (18 × 15 × 13 mm) without obvious adenoma. Laboratory testing revealed elevated serum prolactin (185 μg/L normal, 35.0 μg/L. His height Z-score was +4.89, and weight Z-score was +5.57. He complained of sporadic headaches and had coarse facial features. A 4-year-old boy presented with rapid growth over the previous 2 years.
