Normal Adult Height in an Untreated Boy With McCune-Albright Syndrome Presenting With Precocious Puberty

BACKGROUND/OBJECTIVE: We present a boy with McCune-Albright syndrome (MAS)-associated precocious puberty (PP) who achieved normal adult height without treatment. CASE REPORT: The patient presented at 10 years of age with PP and fibrous dysplasia of the right humerus. Examination showed a height 148.7 cm, Tanner 2 pubic hair and 12-15 cc testes. The Bone age (BA) was 13 years with a predicted adult height of 175 cm vs. mid parental target height of 173 cm. Laboratory parameters were as follows: luteinizing hormone (LH) 0.745 mIU/mL (0.2-4.9 mIU/mL), follicle stimulating hormone (FSH) 0.933 mIU/mL (1.8-3.2 mIU/mL), testosterone 42 ng/dL (18-150 ng/dL), inhibin B 436.6 pg/mL (41-238 pg/mL) and AMH 36.1 ng/mL (45.26-191.34 ng/mL). The DNA testing result of tissue from the right humerus was positive for GNAS p. R201C mutation confirming a diagnosis of MAS. Pubertal progression with growth spurt occurred over the next 3 years: growth velocity (GV) 12 cm/y, testosterone 116 ng/dL, LH 0.715 mIU/mL and FSH 1.3 mIU/mL at 10.6 years; GV 10.3 cm/y, BA 13 to 13.6 years, testosterone 450 ng/dL, LH 1.7 mIU/mL and FSH 1.4 mIU/mL at 11.7 years; and GV 3.8 cm/y, BA 17 years, Testosterone 668 ng/dL and LH 4.2 μIU/mL at 13.3 years. Height was 171.2 cm. DISCUSSION: PP is reported in approximately 15% of boys with MAS. PP leads to BA advancement and reduction in final adult height. Our patient achieved normal adult height without treatment in the absence of excess growth hormone. CONCLUSION: Boys with MAS and PP with slow BA advancement may achieve normal adult height without treatment even in the absence of excess growth hormone.