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At a glance

A very rare congenital genetic disorder characterized by bone lesions that can degenerate into sarcoma. Association with precocious puberty and other hormonal dysfunctions is possible. It is either monostotic fibrous dysplasia or polyostotic fibrous dysplasia with café-au-lait spots without endocrine dysfunction. It is a benign disorder that does not transform into bone cancer. The bone or bones that are affected are usually established early in life and it is very rare for new bones to become affected.

Synonyms

Fibrous Bone Dysplasia; Fibrous Osteoma.

History

It was first described in the medical literature in 1938 by Dr Lichtenstein and in 1942 by Drs Lichtenstein and Jaffe.

Incidence

Fewer than 100 cases reported in the literature. Fibrous dysplasia affects males and females in equal numbers. The disorder is diagnosed early in young children. The exact incidence and prevalence of the disorder is unknown.

Genetic inheritance

Almost sporadic; familial cases have been described.

Pathophysiology

Caused by sporadic mutation of the GNAS1 gene that encodes the alpha subunit of the stimulatory G protein (G1 medullary bone is replaced by fibrous tissue, which appears radiolucent on radiographs). Trabeculae of woven bone contain fluid-filled cysts that are embedded largely in collagenous fibrous matrix. Two types of fibrous bone dysplasia have been described: 1) monostotic (only one bone affected) and 2) polyostotic (the disorder can be widespread and affects multiple bones).

Jaffe-Lichtenstein Syndrome: Facial asymmetry caused by Jaffe-Lichtenstein Syndrome in a 14-year-old girl.

Diagnosis

Onset generally between the ages of 3 and 15 years; clinically evocated by uneven growth, pain, brittleness, and deformity of bone (particularly long bones).

Clinical aspects

May involve a single bone or multiple bones. Bone manifestations are consequences of fibrous lesions that can lead to pathologic fractures, limping, unequal limp length, chest deformity, skull asymmetry, leontiasis-like appearance, and scoliosis. Sarcomatous degeneration has been described in approximately 0.5% of patients. Irregular macular dermal pigmentation can be observed. Other features can include precocious puberty, hyperthyroidism, Cushing disease, hyperparathyroidism, and hypophosphatemia.

Precautions before anesthesia

Because of the dysmorphism affecting the lower part of the face, complete evaluation of the airway must be performed. A complete evaluation of the bone lesion and the possibility of endocrine involvement (clinical, laboratory investigation including alkaline phosphatases, calcemia, phosphatemia, vitamin D levels, thyroid hormones, gonadotropin, and gonadosteroids) must be evaluated. The association with endocrine anomalies is rare.

Anesthetic considerations

Be prepared for difficult direct laryngoscopy and tracheal intubation. Spontaneous respiration may have to be maintained until the trachea is secured. Careful intraoperative positioning ...

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