Fibrous dysplasia is a mosaic disease that can involve any part or combination of the craniofacial, axillary, and/or appendicular skeleton. The type and severity of the complications therefore depend on the location and extent of the affected skeleton. The clinical spectrum is very broad, ranging from an isolated, asymptomatic monostotic lesion discovered incidentally, to severe disabling disease involving practically the entire skeleton and leading to loss of vision, hearing, and/or mobility.

Individual bone lesions typically manifest during the first few years of life and expand during childhood. The vast majority of clinically significant bone lesions are detectable by age 10 years, with few new and almost no clinically significant bone lesions appearing after age 15 years. Total body scintigraphy is useful to identify and determine the extent of bone lesions, and should be performed in all patients with suspected fibrous dysplasia.

Children with fibrous dysplasia in the appendicular skeleton typically present with limp, pain, and/or pathologic fractures. Frequent fractures and progressive deformity may lead to difficulties with ambulation and impaired mobility. In the craniofacial skeleton, fibrous dysplasia may present as a painless “lump” or facial asymmetry. Expansion of craniofacial lesions may lead to progressive facial deformity. In rare cases patients may develop vision and/or hearing loss due to compromise of the optic nerves and/or auditory canals, which is more common in patients with McCune-Albright syndrome associated growth hormone excess. Fibrous dysplasia commonly involves the spine, and may lead to scoliosis, which in rare instances may be severe. Untreated, progressive scoliosis is one of the few features of fibrous dysplasia that can lead to early fatality.

Bone pain is a common complication of fibrous dysplasia. It may present at any age, but most commonly develops during adolescence and progresses into adulthood.

Bone marrow stromal cells in fibrous dysplasia produce excess amounts of the phosphate-regulating hormone fibroblast growth factor-23 (FGF23), leading to loss of phosphate in the urine. Patients with hypophosphatemia may develop rickets/osteomalacia, increased fractures, and bone pain.

Fibrous dysplasia is a disorder where normal bone and marrow is replaced with fibrous tissue, resulting in formation of bone that is weak and prone to expansion. As a result, most complications result from fracture, deformity, functional impairment, and pain. Disease occurs along a broad clinical spectrum ranging from asymptomatic, incidental lesions to severe disabling disease. Disease can affect one bone (monostotic) or multiple (polyostotic), and may occur in isolation or in combination with cafe-au-lait skin macules and hyperfunctioning endocrinopathies, termed McCune-Albright syndrome. More rarely, fibrous dysplasia may be associated with intramuscular myxomas, termed Mazabraud's syndrome. Fibrous dysplasia is very rare, and there is no known cure. Fibrous dysplasia is not a form of cancer.

"Fibrous dysplasia" causes bone thinning and growths or lesions in one or more bones of the human body.

These lesions are tumor-like growths that consist of replacement of the medullary bone with fibrous tissue, causing the expansion and weakening of the areas of bone involved. Especially when involving the skull or facial bones, the lesions can cause externally visible deformities. The skull is often, but not necessarily, affected, and any other bone(s) can be involved.

"Cleidocranial dysostosis" is a general skeletal condition named for the collarbone (cleido-) and cranium deformities which people with it often have. Common features include:

- Partly or completely missing collarbones.

- A soft spot or larger soft area in the top of the head where the fontanelle failed to close.

- Bones and joints are underdeveloped.

- The permanent teeth include supernumerary teeth.

- Permanent teeth not erupting

- Bossing (bulging) of the forehead.

- Hypertelorism

Monostotic fibrous dysplasia (or monostotic osteitis fibrosa) is a form of fibrous dysplasia where only one bone is involved. It comprises a majority of the cases of fibrous dysplasia.

A rare bone disorder characterized by benign bone growths which can cause very painful swellings and bone deformities and makes bone prone to fractures.

The tibia is the most commonly involved bone, accounting for 85% of cases. It is usually painless, although there may be localized pain or fracture, and presents as a localized firm swelling of the tibia in children less than two decades old (median age for males 10, females 13). Several authors have related this non-neoplastic lesion to adamantinoma - a tumor involving subcutaneous long bones - stating the common cause to be fibrovascular defect. However, the latter is distinguished from an osteofibrous dysplasia by the presence of soft tissue extension, intramedullary extension, periosteal reaction and presence of hyperchromic epithelial cells under the microscope.

Osteofibrous dysplasia may also be mistaken for fibrous dysplasia of bone, although osteofibrous dysplasia is more likely to show an immunohistochemical reaction to osteonectin, neurofibromin, and S-100 protein.

Fibrochondrogenesis is a congenital disorder presenting several features and radiological findings, some which distinguish it from other osteochondrodysplasias. These include: fibroblastic dysplasia and fibrosis of chondrocytes (cells which form cartilage); and flared, widened

long bone metaphyses (the portion of bone that grows during childhood).

Other prominent features include dwarfism, shortened ribs that have a appearance, micrognathism (severely underdeveloped jaw), macrocephaly (enlarged head), thoracic hypoplasia (underdeveloped chest), enlarged stomach, platyspondyly (flattened spine), and the somewhat uncommon deformity of tongue (in which the tongue appears split, resembling that of a reptile).

The afflicted may have relatively small amounts of pain that will quickly increase in severity over a time period of 6–12 weeks. The skin temperature around the bone may increase, a bony swelling may be evident, and movement may be restricted in adjacent joints.

Spinal lesions may cause quadriplegia and patients with skull lesions may have headaches.

For unknown reasons, children born with FOP have deformed big toes, possibly missing a joint or simply presenting with a notable lump at the minor joint. The first "flare-up" that leads to the formation of FOP bones usually occurs before the age of 10. The bone growth progresses from the top downward, just as bones grow in fetuses. A child with FOP will typically develop bones starting at the neck, then on the shoulders, arms, chest area and finally on the feet.

Specifically, ossification is typically first seen in the dorsal, axial, cranial and proximal regions of the body. Later the disease progresses in the ventral, appendicular, caudal and distal regions of the body. However, it does not necessarily occur in this order due to injury-caused flare-ups. Often, the tumor-like lumps that characterize the disease appear suddenly. This condition causes loss of mobility to affected joints, including inability to fully open the mouth limiting speech and eating. Extra bone formation around the rib cage restricts the expansion of lungs and diaphragm causing breathing complications.

Since the disease is so rare, the symptoms are often misdiagnosed as cancer or fibrosis. This leads physicians to order biopsies, which can exacerbate the growth of these lumps. However, those born with FOP tend to have malformed toes or thumbs which help distinguish this disorder from other skeletal problems.

The median age of survival is 40 years with proper management. However, delayed diagnosis, trauma and infections can decrease life expectancy.

Polyostotic fibrous dysplasia is a form of fibrous dysplasia affecting more than one bone.

McCune-Albright syndrome includes polyostotic fibrous dysplasia as part of its presentation.

One treatment that has been used is bisphosphonates.

Osteofibrous dysplasia (also known as ossifying fibroma) is a rare, benign non-neoplastic condition with no known cause. It is considered a fibrovascular defect. Campanacci described this condition in two leg bones, the tibia and fibula, and coined the term. This condition should be differentiated from Nonossifying fibroma and fibrous dysplasia of bone.

Commonly affected sites are metaphyses of vertebra, flat bones, femur and tibia. Approximate percentages by sites are as shown:

- Skull and mandible (4%)

- Spine (16%)

- Clavicle and ribs (5%)

- Upper extremity (21%)

- Pelvis and sacrum (12%)

- Femur (13%)

- Lower leg (24%)

- Foot (3%)

The most common locations are the shaft and epyphises of long bones (fibula and humerus) but the spine, metatarsal bones, and ilium have been involved as well. Radiologic examination evidences osteolytic areas with a lobulated framework comprising radiolucent and radiodense foci admixed to speckled calcification. Cortical destruction is a common finding with no soft tissue expansion in many cases. Histopathology of the lesion shows large areas of mature fibrous stroma undergoing hyaline cartilage metaplasia resulting in conspicuous lobules or gradual transformation into chondroid foci. Both hyaline cartilage and chondroid in turn undergo calcification and endochondral cancellous bone formation mimicking epiphyseal plate-like cartilage.

Differential diagnosis is concerned with fibrocartilaginous dysplasia of bone, desmoplastic fibroma, low-grade fibrosarcoma, chondromyxoid fibroma and low-grade chondrosarcoma.

A full account of imaging findings on radiography, bone scan, CT and magnetic resonance has been provided by Sumner et al.

Fibrocartilaginous mesenchymoma of bone is (FCMB) is an extremely rare tumor first described in 1984. Fewer than 20 cases have been reported, with patient ages spanning from 9 to 25 years, though a case in a male infant aged 1 year and 7 months has been reported. Quick growth and bulky size are remarkable features of this tumor.

People with spondyloepiphyseal dysplasia are short-statured from birth, with a very short trunk and neck and shortened limbs. Their hands and feet, however, are usually average-sized. This type of dwarfism is characterized by a normal spinal column length relative to the femur bone. Adult height ranges from 0.9 meters (35 inches) to just over 1.4 meters (55 inches). Curvature of the spine (kyphoscoliosis and lordosis) progresses during childhood and can cause problems with breathing. Changes in the spinal bones (vertebrae) in the neck may also increase the risk of spinal cord damage. Other skeletal signs include flattened vertebrae (platyspondyly), a hip joint deformity in which the upper leg bones turn inward (coxa vara), and an inward- and downward-turning foot (called clubfoot). Decreased joint mobility and arthritis often develop early in life. Medical texts often state a mild and variable change to facial features, including cheekbones close to the nose appearing flattened, although this appears to be unfounded. Some infants are born with an opening in the roof of the mouth, which is called a cleft palate. Severe nearsightedness (high myopia) is sometimes present, as are other eye problems that can affect vision such as detached retinas. About one-quarter of people with this condition have mild to moderate hearing loss.

The appearance of people with the disorder is caused by a loss of bone in the mandible which the body replaces with excessive amounts of fibrous tissue. In most cases, the condition fades as the child grows, but in a few even rarer cases the condition continues to deform the affected person's face. Cherubism also causes premature loss of the primary teeth and uneruption of the permanent teeth.

The condition Cherubism is a rare autosomal dominant disease of the maxilla and mandible. Approximately 200 cases have been reported by medical journals with the majority being males. Cherubism is usually first diagnosed around age 7 and continues through puberty and may or may not continue to advance with age. The degrees of Cherubism vary from mild to severe. Osteoclastic and osteoblastic remodeling contributes to the change of normal bone to fibrous tissue and cyst formation. As noted by the name, the patient's face becomes enlarged and disproportionate due to the fibrous tissue and atypical bone formation. The sponge-like bone formations lead to early tooth loss and permanent tooth eruption problems. The condition also affects the orbital area, creating an upturned eye appearance. The cause of cherubism is believed to be traced to a genetic defect resulting from a mutation of the SH3BP2 gene from chromosome 4p16.3. While the condition is rare and painless, the afflicted suffer the emotional trauma of disfigurement. The effects of Cherubism may also interfere with normal jaw motion and speech. Currently, removal of the tissue and bone by surgery is the only treatment available. This condition is also one of the few that unexpectedly stops and regresses. Normal bone remodeling activity may resume after puberty.

Cherubism is displayed with genetic conformation and when excessive osteoclasts are found in the affected areas of the mandible and maxilla. Large cysts will be present with excessive fibrous areas inside the bone. The fibers and cysts will be found among the trabecula of the Coronoid process, the ramus of mandible, the body of mandible and the maxilla regions. The maxilla will be affected up to and including the orbits and sometimes inside the lower orbits. The maxilla and zygomatic bones are depressed and eyes appear to gaze upward. The maxilla has been found to be more severely affected in most cases than the mandible bone. Some patients found with lower inner orbital growths and cysts may lose vision.

In contrast to STD, the subtype spondylocostal dysostosis, or SCD features intrinsic rib anomalies, in addition to vertebral anomalies. Intrinsic rib anomalies include defects such as birfurcation, broadening and fusion that are not directly related to the vertebral anomalies (such as in STD, where extensive posterior rib fusion occurs due to segmentation defects and extreme shortening of the thoracic vertebral column). In both subtypes, the pulmonary restriction may result in pulmonary hypertension, and have other potential cardiac implications.

Spondylothoracic dysplasia, or STD, has been repeatedly described as an autosomal recessively inherited condition that results in a characteristic fan-like configuration of the ribs with minimal intrinsic rib anomalies. Infants born with this condition typically died early in life due to recurrent respiratory infections and pneumonia due to their restricted thorax. Recently, a report has documented that actual mortality associated with STD is only about 50%, with many survivors leading healthy, independent lives.

Fibrochondrogenesis is a rare autosomal recessive form of osteochondrodysplasia, causing abnormal fibrous development of cartilage and related tissues.

It is a lethal rhizomelic (malformations which result in short, underdeveloped limbs) form of dwarfism, exhibiting both skeletal dysplasia (malformations of bone) and fibroblastic dysplasia (abnormal development of fibroblasts, specialized cells that make up fibrous connective tissue, which plays a role in the formation of cellular structure and promotes healing of damaged tissues). Death caused by complications of fibrochondrogenesis occurs in infancy.

Prenatal and neonatal diagnosis of boomerang dysplasia includes several prominent features found in other osteochondrodysplasias, though the "boomerang" malformation seen in the long bones is the delineating factor.

Featured symptoms of boomerang dysplasia include: dwarfism (a lethal type of infantile dwarfism caused by systemic bone deformities), underossification (lack of bone formation) in the limbs, spine and ilium (pelvis); proliferation of multinucleated giant-cell chondrocytes (cells that produce cartilage and play a role in skeletal development - chondrocytes of this type are rarely found in osteochondrodysplasias), brachydactyly (shortened fingers) and (undersized, shortened bones).

The characteristic "boomerang" malformation presents intermittently among random absences of long bones throughout the skeleton, in affected individuals. For example, one individual may have an absent radius and fibula, with the "boomerang" formation found in both ulnas and tibias. Another patient may present "boomerang" femora, and an absent tibia.

This condition is also characterized by an unusual clubfoot with twisting of the metatarsals, inward- and upward-turning foot, tarsus varus, and inversion adducted appearances. Furthermore, they classically present with scoliosis (progressive curvature of the spine), and unusually positioned thumbs (hitchhiker thumbs). About half of infants with diastrophic dysplasia are born with an opening in the roof of the mouth called a cleft palate. Swelling of the external ears is also common in newborns and can lead to thickened, deformed ears.

The signs and symptoms of diastrophic dysplasia are similar to those of another skeletal disorder called atelosteogenesis, type 2; however diastrophic dysplasia tends to be less severe.

Because collagen plays an important role in the development of the body, people with Kniest Dysplasia will typically have their first symptoms at birth. These symptoms can include:.

- Musculoskeletal Problems

- Short limbs

- Shortened body trunk

- Flattened bones in the spine

- kyphoscoliosis

- Scoliosis (Lateral curvature of the spine)

- Early development of arthritis

- Respiratory problems

- Respiratory tract infection

- Difficulty breathing

- Eye problems

- Severe myopia (near-sightedness)

- Cataract (cloudiness in the lens of the eye)

- Hearing problems

- progressive hearing loss

- ear infections

Most symptoms are chronic and will continue to worsen as the individual ages. It is essential to have regular checkups with general doctors, orthopedist, ophthalmologists, and/or otorhinolaryngologists. This will help to detect whether there are any changes that could cause concern.

This condition is a skeletal dysplasia characterized by short stature, mild brachydactyly, kyphoscoliosis, abnormal gait, enlarged knee joints, precocious osteoarthropathy, platyspondyly, delayed epiphyseal ossification, mild metaphyseal abnormalities, short stature and short and bowed legs. Intelligence is normal.

Some patients may manifest premature pubarche and hyperandrogenism.

Other features that may form part of the syndrome include precocious costal calcification, small iliac bones, short femoral necks, coxa vara, short halluces and fused vertebral bodies.

Cherubism is a rare genetic disorder that causes prominence in the lower portion in the face. The name is derived from the temporary chubby-cheeked resemblance to putti, often confused with cherubs, in Renaissance paintings.

Fibrodysplasia ossificans progressiva (FOP) is an extremely rare connective tissue disease. The disease is caused by a mutation of the body's repair mechanism, which causes fibrous tissue (including muscle, tendon, and ligament) to be ossified spontaneously or when damaged. In many cases, injuries can cause joints to become permanently frozen in place. Surgical removal of the extra bone growths has been shown to cause the body to "repair" the affected area with even more bone.