Imaging description

Incidentally identified bone lesions in the sphenoid are common in the area of liberal CT imaging for common conditions such as sinusitis and headache. Incidental sphenoid bone lesions are rarely malignant. The most common intrinsic benign bone lesions of the sphenoid include fibrous dysplasia (FD) and ossifying fibromas, with rare lesions including giant cell tumors, giant cell reparative granulomas, osteoblastomas, lipomas, and hemangiomas. Although benign, these lesions can become symptomatic secondary to bone expansion and obstruction of sinus drainage or compression of adjacent structures such as cranial nerves and extraocular muscles. Because of this potential many of these lesions require clinical work-up, imaging follow-up and surgery if the symptoms warrant.

Separate from these benign tumors and much more common is a condition called pseudolesion or arrested pneumatization of the sphenoid bone, which is incompletely understood but presumably a developmental condition with no growth potential. These lesions are always asymptomatic; they show a well-defined sclerotic margin, internal curvilinear calcifications intermixed with fat, and lack of bone expansion (Figs. 58.1–58.4). They are almost always associated with underdevelopment of the ipsilateral sphenoid sinus and are thought to occur as a result of premature arrest of pneumatization of the sphenoid sinus.