McCune-Albright syndrome

Abstract

McCune-Albright syndrome (MAS) is classically defined by the clinical triad of fibrous dysplasia of bone (FD), café-au-lait skin spots, and precocious puberty (PP). It is a rare disease with estimated prevalence between 1/100,000 and 1/1,000,000. FD can involve a single or multiple skeletal sites and presents with a limp and/or pain, and, occasionally, a pathologic fracture. Scoliosis is common and may be progressive. In addition to PP (vaginal bleeding or spotting and development of breast tissue in girls, testicular and penile enlargement and precocious sexual behavior in boys), other hyperfunctioning endocrinopathies may be involved including hyperthyroidism, growth hormone excess, Cushing syndrome, and renal phosphate wasting. Café-au-lait spots usually appear in the neonatal period, but it is most often PP or FD that brings the child to medical attention. Renal involvement is seen in approximately 50% of the patients with MAS. The disease results from somatic mutations of the GNAS gene, specifically mutations in the cAMP regulating protein, Gs alpha. The extent of the disease is determined by the proliferation, migration and survival of the cell in which the mutation spontaneously occurs during embryonic development. Diagnosis of MAS is usually established on clinical grounds. Plain radiographs are often sufficient to make the diagnosis of FD and biopsy of FD lesions can confirm the diagnosis. The evaluation of patients with MAS should be guided by knowledge of the spectrum of tissues that may be involved, with specific testing for each. Genetic testing is possible, but is not routinely available. Genetic counseling, however, should be offered. Differential diagnoses include neurofibromatosis, osteofibrous dysplasia, non-ossifying fibromas, idiopathic central precocious puberty, and ovarian neoplasm. Treatment is dictated by the tissues affected, and the extent to which they are affected. Generally, some form of surgical intervention is recommended. Bisphosphonates are frequently used in the treatment of FD. Strengthening exercises are recommended to help maintaining the musculature around the FD bone and minimize the risk for fracture. Treatment of all endocrinopathies is required. Malignancies associated with MAS are distinctly rare occurrences. Malignant transformation of FD lesions occurs in probably less than 1% of the cases of MAS.

Incidence of surgical site infection following adult spinal deformity surgery: an analysis of patient risk

“…In general, surgeries performed for spinal deformities (scoliosis or kyphosis) are felt to be at higher risk for SSI than other spinal surgeries due to prolonged surgical times, larger blood loss, and larger number of levels fused [25][26][27][28][29]. However, few researchers have looked at this high risk group.…”

McCune-Albright Syndrome Mimicking Malignancy: an Endocrine Disease From Oncologist’s Perspective

“…FD may exist in a monostotic or polyostotic form. MAS is characterized by a combination of FD, cutaneous pigmentation, and endocrine abnormalities (2). The mutations in the regulatory Gsα protein - G protein α subunit - (encoded by the [i]GNAS[/i] gene) are the underlying molecular etiology of MAS.…”

“…70-80% of FD cases are monostotic and 20-30% are polyostotic (1). McCune-Albright syndrome (MAS) is defined by the triad of FD, café au lait spots, and precocious puberty or at least one of the typical hyperfunctioning endocrinopathies in almost any possible combination (2). Bone lesions observed in MAS and FD can mimic malignant processes (3).…”

CORR Insights ® : What Is the Role of Allogeneic Cortical Strut Grafts in the Treatment of Fibrous Dysplasia of the Proximal Femur?

“…The disease process is caused by a postzygotic (somatic) mutation of the GNAS gene, manifesting in poorly functioning osteocytes, which produce an inferior quality fibro-osseous bone [9]. The extent of the disease, as well as its extraskeletal manifestations (such as McCune-Albright Syndrome), depends upon the eventual location of the migrating, abnormal embryonic cells [2,10].…”