Perineural spread of malignant melanoma of the head and neck: clinical and imaging features.
OBJECTIVE
Extension of malignant melanoma along cranial nerves is a little-known complication of malignant melanoma of the head and neck. We describe the clinical and MR imaging findings of perineural spread of malignant melanoma to cranial nerves, emphasizing that this entity occurs more commonly with desmoplastic histology and may have a long latent period following primary diagnosis.


METHODS
At two institutions, we identified and retrospectively reviewed eight cases of malignant melanoma of the head and neck that had MR imaging evidence of perineural spread of disease. All patients underwent confirmatory tissue sampling.


RESULTS
Seven patients had melanomas of the facial skin or lip, and one patient had a primary sinonasal lesion. By histopathology, these melanomas included five desmoplastic, two mucosal, and one poorly differentiated melanotic spindle-cell tumor. All patients developed symptomatic cranial neuropathy an average of 4.9 years from the time of initial diagnosis. MR imaging demonstrated postgadolinium enhancement of at least one branch of the trigeminal nerve in all cases and of at least one other cranial nerve in five cases. Other findings included abnormal contrast enhancement and soft tissue thickening in the cavernous sinus, Meckel's cave, and/or the cisternal segment of the trigeminal nerve.


CONCLUSIONS
Although perineural spread of disease occurs most commonly with squamous cell carcinoma and adenoid cystic carcinoma, malignant melanoma must also be included in this differential diagnosis, particularly if the patient's pathology is known to be desmoplastic. Similarly, any patient with malignant melanoma of the head and neck who undergoes MR imaging should receive an imaging assessment focused on the likely routes of perineural spread.
Chang
Patrick C
PC
Department of Radiology, University of California, San Francisco, School of Medicine, San Francisco, CA 94143, USA.
Fischbein
Nancy J
NJ
McCalmont
Timothy H
TH
Kashani-Sabet
Mohammed
M
Zettersten
Elizabeth M
EM
Liu
Amon Y
AY
Weissman
Jane L
JL
D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D044963:Biopsy, Fine-Needle; D003390:Cranial Nerve Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary / Q000628:therapy; D018450:Disease Progression; D004198:Disease Susceptibility / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000628:therapy; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008545:Melanoma / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000628:therapy; D008875:Middle Aged; D016634:Radiosurgery; D011878:Radiotherapy; D012189:Retrospective Studies; D012307:Risk Factors; D016019:Survival Analysis; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome