What are the symptoms of McCune-Albright syndrome (MAS)?

MAS symptoms can vary from mild to severe. They may begin at birth or later in childhood.1

Main Symptoms

Many people with MAS have the following symptoms:

  • Café-au-lait spots
    Café-au-lait (French for "coffee with milk") spots, which are light-brown birthmarks. The birthmarks2,3:
    • Are sually are present at birth
    • May be hard to see on dark skin
    • Often appear on one side of the body
    • Have jagged edges sometimes referred to as the "coast of Maine"
  • Polyostotic fibrous dysplasia2,3
    A person with polyostotic fibrous dysplasia (PFD) has scar-like tissue, or fibrous tissue, in his or her bones. PFD usually occurs on one side of the body in weight-bearing bones, such as leg bones. PFD may cause:
    • Bone pain
    • Cancer of the bone (very rare)
    • Abnormal bone growth
    • Fractures
    • Limping
    • Scoliosis (pronounced skoh-lee-OH-sis), a curvature of the spine
    • Uneven growth, including uneven growth of the face

In addition, bone lesions in the skull may pinch nerves that affect a person’s ability to see and hear.3

  • Precocious puberty2,3,4
    Precocious puberty is when sexual and physical changes occur earlier than normal.

    Girls with MAS may experience such symptoms as:
    • Early menstrual bleeding, usually before 2 years of age
    • Early breast growth
    • Beginning to grow faster
    Boys with MAS are less likely to experience early puberty. Symptoms in boys include:
    • Faster than normal growth of penis or testicles
    • Premature sexual behavior
    • Early growth of armpit or pubic hair

Additional Symptoms

Additional features of MAS may include (but are not limited to)1,2,3,6:

  • Overproduction of growth hormone from the pituitary gland
  • Cushing syndrome, overactivity of the adrenal glands, leading to an increase in stress hormone levels
  • Formation of benign (noncancerous) tumors in the testicles, called Sertoli cell hyperplasia and Leydig cell hyperplasia
  • Hyperthyroidism (pronounced hahy-per-THAHY-roi-diz-uhm), an overactive thyroid gland
  • Loss of phosphate in the urine, leading to low blood phosphorus levels
  • Liver disease


  1. De Sanctis, C., Lala, R., Matarazzo, P., Balsamo, A., Bergamaschi, R., Cisternino, M., et al. (1999). McCune-Albright syndrome: A longitudinal clinical study of 32 patients. Journal of Pediatric Endocrinology and Metabolism, 12, 817-826.
  2. Genetics Home Reference. (2012). McCune-Albright syndrome. Retrieved May 24, 2012, from https://ghr.nlm.nih.gov/condition/mccune-albright-syndrome
  3. Orphanet Journal of Rare Diseases, 3, 12. Retrieved June 21, 2012, from http://www.ojrd.com/content/3/1/12 External Web Site Policy
  4. National Library of Medicine. Precocious puberty. (2011). Retrieved June 21, 2012, from https://www.nlm.nih.gov/medlineplus/ency/article/001168.htm
  5. MedlinePlus. Precocious puberty. (2011). Retrieved June 21, 2012, from https://www.nlm.nih.gov/medlineplus/ency/article/001168.htm
  6. National Library of Medicine. (2010). McCune-Albright syndrome. Retrieved May 10, 2012, from https://www.nlm.nih.gov/medlineplus/ency/article/001217.htm

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