General Information

Description - Definition

Fibrous bone dysplasia is a congenital, non-hereditary disease characterized by bone pain, bone malformations and fractures of one or more bones.

Relevant disease coding (ICD10)

• K10.8 Other specific diseases of the jaws
•  M85.0 Fibrous dysplasia (monostatic form)
  Q78.1 Polyotic fibrous dysplasia

   

Types - Forms

Fibrous dysplasia can be distinguished into the following types:

• Monocytic fibrous dysplasia
  
  • the damage is limited to a single bone
  • answers in 60% of cases
• Polyostotic fibrous dysplasia
  
  • multiple lesions in more bones
  • characterized by renal phosphorus loss
  • answers in 40% of cases

Epidemiology

Impact - Prevalence

It accounts for 2.5% of all benign bone diseases.

Usually the first symptoms appear in childhood with the same frequency in both sexes.

Related situations

Fibrous dysplasia may be associated with:

• endocrinological abnormalities (in 5% of patients), especially with precocious puberty
• McCune-Albright syndrome
  
  • association of fibrous dysplasia with endocrine abnormalities and cafe au lait spots
  • cafe au lait spots are broad brown spots on the skin (coffee with milk), which may be present at birth or appear during childhood (the presence of more than 6 cafe au lait spots is a diagnostic criterion for the diagnosis of neurofibromatosis)
  • scoliosis
    • exists in 40% of cases involving the vertebrae
• congenital pseudoarthrosis (rare)

Reason - Pathogenesis

Reason

The main causative factors of fibrous dysplasia are:

• genetic causes not related to heredity
• missense mutation occurring post-zygotic in the gene encoding the alpha-subunit of the regulatory G-protein in the case of GNAS (guanine nucleotide binding, alpha stimulating gene mutation) on chromosome 20q11 (gsp mutation)