Benign bony lesions of paranasal sinuses and skull base: from osteoma to fibrous dysplasia.

PURPOSE OF REVIEW:Benign bony lesions of the craniofacial complex are relatively common. However, their location close to critical neurovascular structures may render their treatment, if required, highly challenging.This article reviews the current literature on their pathophysiology, diagnosis, natural course and treatment, with a focus on most recent findings. RECENT FINDINGS:A new classification has been suggested concerning endoscopic resectability. The ratio of lateral frontal to interorbital distance can accurately and reliably predict the endoscopic reach to lateral frontal sinus, while orbital transposition can assist us in reaching lateral frontal sinus when anatomy is unfavorable. New and combined endoscopic transnasal and transorbital approaches are now in the surgical armamentarium. Prophylactic optic nerve decompression in fibrous dysplasia is absolutely contraindicated as it leads to worse visual outcomes. Radiotherapy of such lesions is of no benefit and may lead to a higher risk of malignant transformation. The presence of Guanine Nucleotide binding protein Alpha Stimulating (GNAS) mutation in chromosome 20 is universally present in fibrous dysplasia and can differentiate them from ossifying fibromas. SUMMARY:Diagnosis and therapeutic management of benign craniofacial bone lesions remains challenging. If surgical treatment is contemplated, the morbidity of the intervention should always be weighed against the potential benefits. Evolution of extended endoscopic endonasal and transorbital surgery means that more lesions can be reached purely endoscopically with better oncological and cosmetic results.