Fibrous Dysplasia

Fibrous Dysplasia

Question. Write a short note on fibrous dysplasia.
Answer. It arises from the bone forming mesenchyme in spongiosa and develops by proliferation of fibrous tissue.

Fibrous Dysplasia Etiopathogenesis

• Developmental: According to Jaffe and Lichtenstein, it is a developmental anomaly led by aberrant activity in bone-forming mesenchymal tissue. As per many of the theories, it is a developmental anomaly as the disease starts in early life and is active during the time of growth period.
• Endocrine disturbance: As per Sternberg and Joseph, the disorder is a complex endocrine disturbance whose cause is local tissue susceptibility.
• Genetic: It occurs due to a postzygotic mutation in GNAS I, i.e., Guanine nucleotide binding protein I gene. If there is a mutation in the early embryonic period, there is the occurrence of a polyostotic type of fibrous dysplasia. Its mutation is in postnatal life, the monostotic type of fibrous dysplasia occurs.

Fibrous dysplasia

Fibrous Dysplasia Classification 

• Monostotic fibrous dysplasia: Only one bone is involved.
• Polyostotic fibrous dysplasia: More than one bone is involved.
  • Jaffe’s type: In this, there is involvement of a variable number of bones along with pigmented lesions of skin or “café-au-lait” spots.
  • Albright’s syndrome: It is the severe form, which involves all the bones of the body, accompanied by pigmented lesions of the skin along with the endocrine disturbances of various types.

Fibrous Dysplasia Clinical Features

• Monostotic fibrous dysplasia.
  • Sites: Involve one bone; no extraskeletal effects are present other than occasional pigmented skin lesions. Most frequent sites are ribs, femur, maxilla, and mandible.
  • Age and sex: Occurs in younger children of 10 years of age.
  • Swelling is present over the affected side.
• Polyostotic fibrous dysplasia.
  • Jaffe’s Type:
    • Involves multiple bones, and the female-to-male ratio is 3:1.
    • Skin consists of irregularly pigmented light brown melanotic spots called “cafe-au-lait spots”.
    • Most common sites are the back, buttocks, thigh, shoulder, chest, neck, and face.
    • Recurrent bone pain is a common problem.
    • Skeletal lesions can be unilateral or may involve all the bones of the body. Lesions get static with cessation of growth, but proliferation continues in polyostotic form.
    • The most common complication is a spontaneous fracture.
    • In very few cases, continuous extension of the disease can lead to destructive deformity and blindness.

Polyostotic fibrous dysplasia

• McCune-Albright syndrome
  • Found more commonly in females.
  • In addition to the bone deformities, it also shows endocrine disturbances such as precocious puberty, goiter, hyperthyroidism, hyperparathyroidism, Cushing’s syndrome, and acromegaly.
  • Café-au-lait spots are commonly seen. These are the coffees with milk color spots. An irregular flat area of increased skin pigmentation is seen.
  • There is the presence of excessive vaginal bleeding.
  • The main sign is the development of secondary sexual features, mainly pubic and Axillary hairs, along with the development of breasts, which occurs at the age of 5 years. It can also result in crippling deformity or a fracture.
  • Mainly, the long bones are the ones that are frequently affected.

Fibrous Dysplasia Oral Manifestations 

• Monostotic
  • Maxilla is more commonly affected, with the majority of changes occurring in the posterior region, i.e., premolar-molar region.
  • There is a presence of unilateral facial swelling, which grows slowly with intact overlying mucosa.
  • Swelling is mainly painless, but in some cases, patients complain of discomfort or frank pain.
  • Buccal and cortical plates become enlarged.
  • If the mandible is involved there is protuberant excrescence of the inferior border of the mandible occurs.
  • In the affected area, teeth become malaligned and tipped, or displaced.
  • Supernumerary teeth can also be encountered. They commonly occur in the maxillary midline or mandibular premolar region. Supernumerary teeth often remain impacted or can affect the eruption of normal teeth.

Fibrous dysplasia treatment

Fibrous Dysplasia Craniofacial

• It involves the maxillary sinus, the zygomatic process, the floor of the orbit, and sometimes the base of the skull.
• This causes severe malocclusion, marked facial deformity, anosmia, deafness, and blindness.
• The most common sign is proptosis of an affected eye.

Fibrous Dysplasia Polyostotic

• Jaws become deformed and show expansion along with symmetry of the facial bones. Ballooning of the jaw is a common characteristic.
• There is a disturbed eruption pattern of teeth due to the loss of support for developing teeth.
• Intraoral pigmentation can also be appreciated in some of the cases.

Fibrous Dysplasia Radiographic Features

Fibrous Dysplasia Diagnosis

• Clinical diagnosis: Presence of painless swelling in the maxillary region along with intact mucosa. Café-au-lait spots are seen.
• Radiographic diagnosis: Both ground glass appearance and granular appearance are seen.
• Laboratory diagnosis:
  • Serum alkaline phosphatase levels are increased.
  • On histological examination, fibrous bone is seen in the compact stroma of interlacing collagen fibers. Irregular trabeculae of bone are seen scattered throughout the lesion with no definite pattern of arrangement. Some of the trabeculae are C-shaped and are revealed as a Characteristic Chinese letter pattern.

Ground glass appearance bone lesion

Fibrous Dysplasia Management

• Surgical removal of the lesion is done.
• Osseous contouring is done to correct deformity for aesthetic purposes.