McCune-Albright syndrome

The McCune-Albright syndrome is a rare genetic disease characterized by the following triad of polyostotic fibrous dysplasia, café au lait skin spots and hyperfunctioning endocrinopathies (such as precocious puberty and hyperthyroidism). It was first described in 1936 by James Donovan McCune, and therefore in 1937 by Albright Fuller.

This syndrome results from a mutation in the gene GNAS1 and is related to mosaicism that occurs early in embryonic stage.

The incidence of this syndrome is not fully known. It is known that equally affects all ethnicities. The gonadotropin-dependent precocious puberty is more observed in females, yet the rest of the manifestations of this syndrome occurs equally in both sexes.

The clinical picture varies, since the disease is highly variable. When fibrous dysplasia polycystic predominates, there may be multiple fractures at onset, especially during childhood. Besides precocious puberty, other endocrinopathies may be present in the McCune-Albright syndrome, as goiter with or without hyperthyroidism, diabetes mellitus, acromegaly, Cushing's syndrome, hyperparathyroidism, hyperprolactinemia and gynecomastia. Between 30% to 40% of patients present with thyroid disorders, especially males, hyperthyroidism being the second most frequent endocrinopathy syndrome.

They may also be observed in patients with this syndrome:

• Deformities of the lower limbs, and posterior skull;

• Stains placement latte;

• Gigantism.

Diagnosis, Treatment and Prevention

The diagnosis is made by physical examination, together with laboratory tests and imaging studies. Among the laboratory tests are checked levels of adrenal hormones, blood prolactin and growth hormone. With respect to imaging tests, may be performed radiography, pelvic ultrasound, bone scan, CT scan of the abdomen and MRI of the head.

The treatment is only symptomatic, since no specific therapy for the syndrome. Aromatase inhibitor drugs are the most used in girls with persistent elevation of estradiol. In cases of fibrodysplasia symptomatic bone, is used bisphosphonates in order to alleviate bone pain. When there dysplastic lesion is recommended surgery.

With regard to hyperthyroidism, treatment includes antithyroid medications. However, the definitive treatment involves ablative therapy or surgery.

Patients presenting with gigantism / acromegaly are treated with somatostatin analogues in cases of adenomas producing growth hormone, the treatment being reserved only for cases of resectable tumors and visible.

There is a way to prevent this syndrome. However, some measures should be adopted to prevent the occurrence of fractures in patients with polyostotic fibrous dysplasia.