Imaging of auriculotemporal nerve perineural spread

Abstract

Importance: Adenoid cystic carcinomas (ACCs) are relatively rare tumours, notorious for wide local infiltration and perineural spread. Perineural extension commonly occurs along branches of the trigeminal and facial nerves, and its presence represents a poor prognostic factor with implications for treatment approach.

Observations: We report the case of a 61-year-old female presenting with worsening left facial numbness and weakness. On magnetic resonance imaging, the patient was found to have perineural spread of a left parotid tumour along the auriculotemporal nerve. There was involvement of the V2 and V3 branches of the trigeminal nerve. An ultrasound-guided biopsy of the mass demonstrated ACC.

Conclusions and relevance: The auriculotemporal nerve may serve as a route for tumour spread, particularly in the setting of head and neck malignancy. Moreover, this particular suspicion should be raised when patients with known malignancy experience concomitant trigeminal (V) and facial (VII) nerve dysfunctions.

Keywords: CT; MRI; head and neck malignancy; perineural spread.

Figure 1.. A contrast-enhanced axial CT image shows an enhancing, lobulated mass in the left preauricular region.

Figure 2 A–C.. Axial T1-weighted image (A) and post-contrast coronal T1-weighted images with fat saturation (B, C) demonstrates a curvilinear band of enhancing tumour (arrows in A, B) that extends from the left parotid mass (asterisk) and tracks behind the mandibular ramus and joins with the V3 nerve in the masticator space. There is contiguous extension along V3 superiorly through a widened foramen ovale (dashed arrow in C) and asymmetric thickening and enhancement of the left cavernous sinus.