Perineural Melanoma

This 76 year-old male patient had a desmoplastic melanoma excised from the left cheek. This series of MR images (coronal T2W, axial and coronal T1W fat-sat post-contrast) shows enlargement and enhancement of the maxillary division of the trigeminal nerve. Click on the image for arrows. There is also left sphenoid sinusitis.
Any malignant tumour may undergo perineural tumour spread. The tumours with the greatest propensity for this form of spread are: adenoid cystic carcinoma; squamous cell carcinoma; desmoplastic melanoma; non-Hodgkin lymphoma; and mucoepidermoid carcinoma. Perineural tumour spread adversely affects patient prognosis, with increased local recurrence, distant metastases and meningeal carcinomatosis.
Reference: Harnsberger R, et al. Diagnostic Imaging: Head and Neck. Amirsys 2004.
Credit: Dr Laughlin Dawes
http://www.radpod.org