Perineural spread of cutaneous squamous and basal cell carcinoma: CT and MR detection and its impact on patient management and prognosis.

PURPOSE: To analyze the pretreatment imaging findings and outcome of patients with perineural spread of squamous or basal cell carcinoma of the face and scalp treated with radiotherapy, to determine whether CT (computed tomography) or MR (magnetic resonance) imaging can be effectively used to identify patients who would benefit from aggressive treatment, and to characterize the imaging features associated with cure.
METHODS: Thirty-five patients had perineural spread of squamous and basal cell carcinoma along the divisions of the trigeminal and/or facial nerves based on clinical findings and/or histopathological proof. Perineural extension seen on imaging was divided into three zones of involvement. The volume of perineural disease was graded semiquanitatively. All patients received radiotherapy with curative intent.
RESULTS: Eighteen of the 35 patients had imaging evidence of perineural spread of tumor, and the remaining 17 were imaging negative for perineural spread. The absolute 5-year survival of the imaging positive group was 50% compared with 86% in the imaging-negative group (p = 0.048).
CONCLUSIONS: Imaging can be used to identify patients with advanced perineural spread who warrant aggressive radiotherapy. Imaging evidence of perineural invasion worsens prognosis; however, low-volume and peripheral perineural disease is radiocurable. Greater perineural tumor volume with more central disease was associated with an unfavorable outcome.