Fibrous dysplasia of the sinonasal tract and adjacent skull base

Fibrous dysplasia is a rare condition characterized by replacement of normal bone by fibro-osseous connective tissue exhibiting varying degrees of osseous metaplasia, which can affect the craniofacial complex. This article reviews the recent literature with the intent to highlight the innovative information that has contributed to elucidate the pathophysiology, diagnostic criteria, and treatment principles of the disease.

A mutation in the GNAS1 gene on chromosome 20 has been identified as the molecular hallmark of fibrous dysplasia. This finding is not present in ossifying fibroma, which has been traditionally included in differential diagnosis. The concept that asymptomatic patients do not require surgical treatment has been reinforced by a meta-analysis specifically addressing the issue of optic nerve decompression.

A diagnosis of fibrous dysplasia can be achieved by combined assessment of clinical, radiologic, and pathologic findings. There is general agreement that, when the disease is not associated with symptoms, partial or radical resection is not indicated, but patients do require periodic radiologic evaluations. There is, however, an absolute need for prospective studies to identify factors predicting the possible late growth of the disease and to investigate the efficacy and side-effects of pharmacological treatment with biphosphonates.