Bookshelf

Suggested evaluations to determine if fibrous dysplasia (FD) is present and the extent of disease if FD is present

⁹⁹Tc-MDP = technetium-99 conjugated with methylene diphosphonate; FD = fibrous dysplasia; H&P = history and physical exam; TRP = tubular reabsorption of phosphate; XR = x-ray

1. Performed at initial presentation in all individuals suspected of having FD/MAS.

2. Areas of clinically significant FD will be apparent on bone scan by age five years. Prior to age five years, a normal ⁹⁹Tc-MDP does not eliminate the possibility of significant FD [Hart et al 2007].

3. FGF23-mediated phosphate wasting is associated with a high FD burden. Phosphate wasting may worsen during rapid skeletal growth and improve or resolve in adulthood as FD becomes less active [Riminucci et al 2003].

4. Consider performing ⁹⁹Tc-MDP bone scan in children younger than age five years regardless of clinical suspicion for bone disease in instances where establishing the diagnosis of MAS may alter management – i.e., those for whom diagnostic surgery is being considered, such as skeletal biopsy.

5. Significance of FD is determined by both the amount and location of affected bone [Collins et al 2005]. Clinically significant disease is frequently associated with the craniofacial area, proximal femurs, and spine.

6. A normal ⁹⁹Tc-MDP bone scan at age five years or older effectively eliminates clinically significant FD, and no further radiologic monitoring is required [Hart et al 2007].