Varied appearance of trigeminal neuroma on CT.

The computed tomographic (CT) scans of five patients with surgically and histologically proven trigeminal neuromas demonstrated the varied appearance of this tumor. In this series, tumors appeared in the middle cranial fossa, the posterior cranial fossa, or extended into both. Prior to contrast infusion, the tumors showed low density, normal brain density, or mixed normal and low density on the CT Scan. After contrast infusion, all tumors were well circumscribed with marked enhancement, which was either homogeneous or inhomogeneous. None of the trigeminal neuromas had surrounding brain edema. The three larger tumors had significant mass effect with hydrocephalus and displacement of the fourth ventricle or compression of adjacent cisterns.