Osteomas are benign, slow growing bony tumors involving the base of the skull and paranasal sinuses. Arising from the normal bony walls of the sinus cavities, osteomas are the most common tumor involving the paranasal sinuses. Causes of osteoma development that have been theorized include congenital, inflammatory, or traumatic factors, but in most cases the cause of the osteoma is unknown.
Osteomas are often discovered incidentally during radiologic imaging of the head or sinuses for other reasons, since osteomas frequently do not cause symptoms. Because osteomas are slow-growing tumors, small incidentally discovered osteomas can simply be observed and remain untreated. However, larger osteomas may cause symptoms if they block sinus drainage, compress nerves, or grow beyond the walls of the sinuses and encroach upon the cranial cavity or structures surrounding the eye. In such cases, a patient may experience sinus infections, facial pain, or headaches, and surgical removal of the osteoma may thus be considered.
A CT scan of the sinuses without intravenous contrast is the definitive study for diagnosis of sinonasal and skull base osteomas. A biopsy is typically not necessary to secure the diagnosis. A CT scan allows the surgeon to assess the size of the osteoma as well as its relationship to critical anatomic structures within the skull. The most common location for a paranasal sinus osteoma is the frontal sinus, followed by the ethmoid, maxillary and sphenoid sinuses. Although the vast majority of osteomas occur sporadically without association with any other diseases or risk factors, in rare cases osteomas may be a component of an underlying hereditary disorder. Gardner Syndrome is an autosomal dominant familial disease that is characterized by multiple osteomas, soft tissue tumors (subcutaneous fibrous tumors or epidermal/sebaceous cysts), and colonic polyposis.
As indicated above, many osteomas do not require surgical removal and can often be observed and monitored conservatively. When surgery is required, osteomas can often be removed using minimally invasive endoscopic techniques, passing instruments and scopes through the nostrils without the need for external incisions. More extensive osteomas may require open approaches through skin incisions along the scalp or face, but in many cases endoscopic techniques can be combined with traditional external approaches in order to minimize the extent of incisions and to shorten recovery.