[Retrograde perineural extension of a metastatic recurrence of a frontal skin tumor].

Perineural metastatic spread of malignant tumours has been described for a long time, but has only recently been demonstrated by medical imaging. MRI, guided by the clinical findings, with fine sections on T1-weighted sequences without and with gadolinium, allows the diagnosis of this type of spread. The tumours most frequently responsible are squamous cell carcinomas and cylindromas. The trigeminal and facial nerves are the most frequently affected. Recognition of such lesions is essential in the initial staging of a malignant tumour of the face, as it alters the therapeutic strategy.