Unraveling the Mosaic: Understanding Polyostotic Fibrous Dysplasia

Expert Reviewed By: ⁠Dr. Brandon Colby MD

Introduction to Polyostotic Fibrous Dysplasia

Polyostotic fibrous dysplasia (PFD) is a rare genetic condition that affects the bones, causing them to become weak and prone to fractures. It is characterized by the presence of fibrous tissue in place of normal bone, leading to pain, deformity, and an increased risk of fractures. PFD is one of the key features of a more complex disorder called McCune-Albright syndrome (MAS), which also includes skin hyperpigmentation and endocrine dysfunction1. The condition has a mosaic nature, affecting various cells, tissues, and organs, leading to a range of clinical signs and prognosis.

Diagnosing Polyostotic Fibrous Dysplasia

Diagnosing PFD can be challenging due to its variable presentation and rarity. The condition is often identified through a combination of physical examination, imaging studies, and laboratory tests. In some cases, a biopsy may be performed to confirm the presence of fibrous tissue in the affected bones1.

One case report described a patient with PFD who experienced acute visual disturbance and forehead enlargement due to a rare complication called aneurysmal bone cyst2. This patient was successfully treated with surgery. Another case report highlighted a young female with PFD, unique physical findings, and gene mutations in HSPG2 and RIMS1, which may contribute to her unusual symptoms3.

Genetic Testing and Polyostotic Fibrous Dysplasia

Although PFD is a genetic condition, it is not typically inherited from one’s parents. Instead, it arises due to somatic mutations that occur in the body’s cells during development. This means that the genetic changes responsible for PFD are present in only some of the body’s cells, creating a mosaic pattern of affected and unaffected tissues1.

Identifying Genetic Mutations

Genetic testing can be helpful in identifying the specific mutations responsible for PFD in an individual. In some cases, this information can provide insight into the severity of the condition and help guide treatment decisions. For example, one case report described a patient with symmetrical PFD who was found to have a specific mutation in the KRAS gene (NM_004985.5):c.57G>C; p.Leu19Phe4. This mutation was thought to contribute to the development of dysplastic bone lesions in patients with this specific genetic change.

Guiding Treatment Decisions

Understanding the genetic basis of PFD can help inform treatment decisions for affected individuals. For example, if a patient is found to have a specific mutation associated with a more severe form of the condition, more aggressive treatment options may be considered. Conversely, if a patient has a mutation associated with a milder form of PFD, a more conservative approach to treatment may be appropriate.

Future Research and Potential Therapies

As our understanding of the genetic basis of PFD continues to grow, it is possible that new treatment options will become available for affected individuals. For example, researchers may be able to develop targeted therapies that specifically address the genetic mutations responsible for PFD, potentially leading to more effective and personalized treatment options.

Conclusion

Polyostotic fibrous dysplasia is a rare and complex genetic condition that can have a significant impact on an individual’s quality of life. Genetic testing can be a valuable tool in diagnosing PFD, understanding its severity, and guiding treatment decisions. As our knowledge of the genetic basis of PFD expands, it is likely that new and more effective treatment options will become available for those affected by this challenging condition.

About The Expert Reviewer

Dr. Brandon Colby MD is a US physician specializing in the personalized prevention of disease through the use of genomic technologies. He’s an expert in genetic testing, genetic analysis, and precision medicine. Dr. Colby is also the Founder of  and the author of ⁠⁠Outsmart Your Genes.

Dr. Colby holds an MD from the Mount Sinai School of Medicine, an MBA from Stanford University’s Graduate School of Business, and a degree in Genetics with Honors from the University of Michigan. He is an Affiliate Specialist of the American College of Medical Genetics and Genomics (⁠⁠ACMG), an Associate of the American College of Preventive Medicine (⁠⁠ACPM), and a member of the National Society of Genetic Counselors (⁠NSGC)