A 4-year-old girl presents with recurrent vaginal bleeding and breast development. Examination shows several large, irregularly bordered cafe-au-lait macules on her trunk. A skeletal survey reveals multiple radiolucent expansile lesions in the proximal femur. LH and FSH are prepubertal despite estradiol being elevated. What is the most likely diagnosis?

• A Gonadotropin-dependent (central) precocious puberty
• B Neurofibromatosis type 1 with optic pathway glioma
• C Juvenile granulosa cell tumour of the ovary
• D McCune-Albright syndrome ✓

Explanation

The triad of peripheral precocious puberty, irregular coast-of-Maine cafe-au-lait macules, and polyostotic fibrous dysplasia defines McCune-Albright syndrome, caused by a somatic activating GNAS mutation producing autonomous ovarian estrogen secretion. Suppressed gonadotropins exclude central precocious puberty. Neurofibromatosis type 1 is the strongest distractor, but its cafe-au-lait spots have smooth coast-of-California borders, and it does not cause autonomous estrogen production. An ovarian tumour gives unilateral pelvic findings, not bony lesions.

Reference: Nelson Textbook of Pediatrics, 22nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.