What is the McCune Albright Syndrome Triad?

McCune-Albright Syndrome is a multisystemic condition, as well as a rare disease, with patients expressing many different symptoms. This can make it difficult to diagnose, or cause a misdiagnosis, which can lead to further complications of using the wrong treatments and surgeries. Historically, McCune-Albright syndrome was defined as a trifecta of observable symptoms (fibrous dysplasia, precocious puberty, and skin spots). Today, we now know that there are multiple possible symptoms that define McCune-Albright syndrome.

McCune-Albright Syndrome can show up in patients in many different ways. For this reason, McCune-Albright syndrome may be difficult to diagnose..

Your specialist may reference the McCune-Albright Syndrome Triad, along with the other symptoms of McCune-Albright syndrome, to help you make a proper diagnosis. This can greatly help you find treatments and management strategies to help you reduce suffering and maximize the enjoyment of life. Being proactive and addressing issues early is one of the most important factors, especially in regards to bone deformity and other physical ailments, if they’re present in your particular case.

It’s important to recognize that the McCune-Albright syndrome triad is an outdated approach to diagnosing FD/MAS. The triad can be misleading in cases where a patient has fibrous dysplasia and excess growth hormone, but no skin spots or precocious puberty, for instance. This is why it’s important for a diagnosis to use a more comprehensive definition of MAS.

The Three Symptoms of the McCune Albright Syndrome Triad

McCune-Albright syndrome is now defined as any combination of the following:

1. Fibrous Dysplasia

Fibrous dysplasia is a rare skeletal disorder in which one or more bones are replaced with fibrous bone tissue. While it most commonly affects bones in the skull and face, it can affect any bone in the body.

Fibrous dysplasia is easy to misdiagnose as it has a number of symptoms that may or may not present themselves, including fragile bones which break easily, bone pain, abnormally shaped bones, and pain or discomfort in the tissues around the affected bones. There are management strategies to help ease discomfort from this condition, although some patients may exhibit no symptoms at all.

While almost all patients with McCune-Albright syndrome have fibrous dysplasia, not all patients with fibrous dysplasia have McCune-Albright syndrome.

2. “Coast of Maine” Birthmarks sometimes known as Café-Au-Lait Spots

Some children are born with light to dark brown birthmarks with rough borders. The spots can appear at birth, or show up later in childhood. These spots are fairly common, with an estimated 10% of all children bearing at least one spot.

The birthmarks primarily show up with rough edges, dubbed a “coast of Maine” birthmark. While the spots themselves are not harmful, in quantity they may be caused by serious underlying health conditions, including McCune-Albright syndrome.

3. Endocrine abnormalities including precocious puberty

Endocrine involvement in McCune-Albright syndrome can appear in a number of different ways including hyperthyroidism, excess growth hormone, low blood phosphorus levels, and high cortisol levels.
Some complications, such as the high cortisol levels known as Cushing’s disease, only appear during infancy. Other endocrinopathies such as low blood phosphorus levels and excess growth hormone should be monitored throughout a patient’s life.

Young girls with McCune-Albright syndrome and Fibrous Dysplasia often also go through precocious puberty. In fact it is the single most common hormonal problem in girls with FD/MAS, but is relatively uncommon in boys. Children with precocious puberty exhibit all the traditional puberty symptoms, such as rapidly increased growth of height, hair, sex hormones, and may develop acne or body odor.

Endocrine abnormalities can stunt growth and lead to further complications if not managed appropriately. The good news is that these hormone imbalances are largely treatable if diagnosed early and the proper steps of care are followed.

Your Key Takeaway When Seeking a McCune-Albright Syndrome Diagnosis

The McCune-Albright Syndrome Triad is an outdated approach to diagnosing FD/MAS. While the three symptoms that the Triad refers to can lead to a diagnosis of FD/MAS, each symptom can appear independently and may have its own unique causes. What’s more, the McCune-Albright syndrome triad does not take into account other hormonal imbalances that could also indicate a diagnosis of FD/MAS. If a patient has any combination of FD bone lesions, skin spots, and hormonal imbalances, they should be evaluated for FD/MAS. This will help them formulate a strategy for long-term treatment and management of the condition.