LAUSR

BACKGROUND Polyostotic fibrous dysplasia (PFD) is an uncommon developmental bone disease in which normal bone and marrow are replaced by pseudotumoral tissue. The etiology of PFD is unclear, but it is generally thought to be caused by sporadic, post-zygotic mutations in the GNAS gene. Herein, we report the case of a young female with bone pain and lesions consistent with PFD, unique physical findings, and gene mutations. CASE SUMMARY A 27-year-old female presented with unbearable bone pain in her left foot for 4 years. Multiple bone lesions were detected by radiographic examinations, and a diagnosis of PFD was made after a biopsy of her left calcaneus with symptoms including pre-axial polydactyly on her left hand and severe ophthalmological problems such as high myopia, vitreous opacity, and choroidal atrophy. Her serum cortisol level was high, consistent with Cushing syndrome. Due to consanguineous marriage of her grandparents, boosted whole exome screening was performed to identify gene mutations. The results revealed mutations in HSPG2 and RIMS1, which may be contributing factors to her unique findings. CONCLUSION The unique findings in this patient with PFD may be related to mutations in the HSPG2 and RIMS1 genes.