A 4-year-old girl has vaginal bleeding, breast development, and irregular cafe-au-lait macules with jagged borders on her trunk. X-ray of the femur shows expansile lytic lesions with ground-glass appearance. GnRH stimulation test shows a prepubertal LH response. What is the diagnosis?

• A McCune-Albright syndrome ✓
• B Central precocious puberty due to hypothalamic hamartoma
• C Familial male-limited precocious puberty
• D Granulosa cell tumour of the ovary

Explanation

McCune-Albright syndrome is caused by a postzygotic activating GNAS mutation producing the triad of peripheral (gonadotropin-independent) precocious puberty, polyostotic fibrous dysplasia, and cafe-au-lait spots with irregular coast-of-Maine borders. The prepubertal LH response on GnRH testing confirms gonadotropin independence, excluding central precocious puberty. Ovarian cysts with autonomous estrogen secretion drive the bleeding. Treatment uses aromatase inhibitors or tamoxifen rather than GnRH analogues.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.