Common fibro-osseous lesions of the paranasal sinuses.

摘要

Osteomas are the most common fibro-osseous lesions in the paranasal sinuses. They are infrequent, with an incidence of 0.43%, and are seen in upto 3% of sinus CT series. Histologically, they are made of dense lamellar bone without haversian canals, or otherwise mature bone. Thus, they appear radiographically as- well-circumscribed dense masses attached to the originating bone by either a broad- or narrow-based pedicle. The three theories of pathogenesis are developmental, traumatic, and infectious. They may arise from residual cartilaginous rests or as a reaction to an inciting event.Most frequently, osteomas are asymptomatic and are discovered incidentally. When they do cause symptoms, headache is most frequent, followed by sinusitis, pain, and facial or cranial deformation. Complications arise when an osteoma has grown large enough to impinge on surrounding structures. Obstructive sinusitis, mucocele formation, and intrusion on the intra-cranial and orbital spaces with resultant maladies have all been reported in association with paranasal sinus osteomas. Treatment is by surgical excision, frequently possible via endoscopic techniques, although some of the more lateral frontal sinus lesions are more easily removed via an osteoplastic or combined approach. It is often necessary to perform a Draf II or III, or an endoscopic modified Lothrop procedure, to gain adequate endoscopic exposure. A surgeon should expect and be prepared to manage periorbital and dural injuries, as they are occasionally unavoidable when removing these lesions via either endoscopic or external approaches.Fibrous dysplasia and ossifying fibroma are other fibro-osseous lesions found in the paranasal sinuses. Fibrous dysplasia affects children and characteristically "burns out" during puberty. It is deforming but not destructive and appears as a ground glass density on plain film radiograph or CT. In the polyostotic form, it is associated with McCune-Albright syndrome. A conservative treatment strategy is recommended, reserving surgical intervention for symptomatic lesions. Ossifying fibroma is more serious. Appearing asa well-circumscribed lesion with an eggshell-thin wall and a hypodense cen-ter, OF can be locally destructive and should be aggressively and completely excised.