Fibrous Dysplasia of Bone and McCune–Albright Syndrome: A Bench to Bedside Review

Abstract

Fibrous dysplasia is an uncommon mosaic disorder in which bone is replaced by structurally unsound fibro-osseous tissue. It is caused by the sporadic post-zygotic activating mutations in GNAS, resulting in dysregulated Gα S-protein signaling in affected tissues. This manifests on a broad clinical spectrum ranging from insignificant solitary lesions to severe disease with deformities, fractures, functional impairment, and pain. Fibrous dysplasia may present in isolation or in association with hyperfunctioning endocrinopathies and café-au-lait macules, known as McCune-Albright Syndrome. This review summarizes current understanding of pathophysiology in fibrous dysplasia, describes key pre-clinical and clinical investigations, and details the current approach to diagnosis and management.

Atypical Femoral Fracture in McCune-Albright Syndrome

“…FD is a rare disorder caused by replacing the normal bone with fibro-osseous tissue so the new skeleton is weaker and the risk of fracture, deformity, and pain is higher [10,13,18,27]. FD was first described by Lichtenstein in 1938 [28,29] and can involve any part of the skeleton, like long bones, craniofacial, and axial skeleton.…”

“…Fibrous Dysplasia (FD) is a rare and asymptomatic mosaic disorder caused by replacing a normal bone with fibro-osseous tissues. The new skeleton is weak and fragile and easy to get deformities and fractures [9][10][11][12][13][14]. FD can affect any part of the body like craniofacial, axial, or appendicular skeleton [15].…”

Kyphotic deformity of the lumbar spine due to a monostotic fibrous dysplasia of the second lumbar vertebra: a case report and its surgical management

“…Nowadays, FD is known as an uncommon mosaic disease, in which normal bone gets replaced by fibro-osseous tissue. This bony remodification leads to a weakened osseous matrix prone to fractures and deformity with corresponding pain and functional impairment [ 8 ]. FD represents 5 to 7% of benign bone tumors [ 4 ].…”

“…The monostotic form of the disease is much more common (80%) than the polyostotic form (20%) [ 4 ]. Extra-osseous involvement of polyostotic fibrous dysplasia (PFD) including the skin (abnormal skin pigmentation) with accompanied precocious puberty, hyperthyroidism, and other extra-skeletal abnormalities presenting as the so called McCune–Albright syndrome was described [ 8 ]. MFD can affect every part of the skeleton, but is commonly found in jaw bones, ribs, femur, and tibia [ 14 ].…”

Focal and Osteosclerotic Bone Diseases

“…Next, Hartley and colleagues provide a detailed bench-tobedside review of fibrous dysplasia and McCune-Albright syndrome [8]. The review covers all aspects of these conditions from their genetic basis and pathophysiology, through to the clinical features and management options.…”