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.