Rhinocerebral mucormycosis with perineural spread.

We describe the histopathologic findings of perineural invasion in orbital mucormycosis in a man with diabetes in ketoacidosis. Linear enhancement on MRI beginning at the orbital apex was correlated with fungal tracking of the trigeminal and lacrimal nerves. Mucormycosis can spread considerable distances from its primary focus of infection along peripheral nerves, a phenomenon that can be identified clinically with contrast-enhanced MRI.