Imaging description

Juvenile nasal angiofibromas (JNAs) are benign, fibrovascular tumors that are locally invasive and infiltrative [1]. Malignant conversion has been reported, but it is rare in tumors that have not been irradiated [2].

CT and MRI play a vital and often complementary role in assessment of these tumors. Axial and coronal CT images with bone windows best demonstrate the degree of bone remodeling and erosion. High-resolution, contrast-enhanced MRI is very useful in demonstrating the soft tissue extent, and to evaluate possible intracranial or cavernous sinus extension. Larger and more vascular tumors display obvious flow voids within the mass, representing intratumoral vessels. The mass typically enhances briskly with contrast, both on MRI and on CT. Differentiation of obstructed sinus secretions versus soft tissue mass from sinus invasion is difficult on CT but easily assessed by MRI.

The tumor is thought to arise from the lateral margin of the posterior nasal cavity, adjacent to the sphenopalatine foramen (Fig. 71.1). Large tumors are dumbbell-shaped or bilobed, with one portion of the tumor bulging into the nasopharynx and the other extending towards the pterygopalatine fossa. These tumors can demonstrate extensive locoregional spread along natural tissue planes. Superiorly, the mass can erode into the sphenoid sinus, cavernous sinus, sella, and middle cranial fossa. Laterally, the tumor may spread into the pterygomaxillary and sphenopalatine fossae. Larger tumors cause a characteristic bowing of the maxillary sinus (Fig. 71.2). Occasionally the mass erode through the greater wing of the sphenoid bone, thereby exposing the dura of the middle cranial fossa.