FIG 3. Axial contrast-agent–enhanced CT images obtained at two levels in a 77-year-old man with metastatic undifferentiated carcinoma and lymphoma who had a left facial mass and facial weakness.

A, Scan shows that a homogeneous soft-tissue mass (m), which extends medially (arrowheads) along the posterior margin of the ramus () of the mandible, almost completely replaces the left parotid gland. This finding was interpreted as suggesting perineural tumor spread along the facial nerve main trunk and auriculotemporal nerve. Pathologic findings, however, did not confirm this. Retrospective review of the CT scans revealed that the soft-tissue mass actually was lower than the expected course of the auriculotemporal nerve.

B, Scan illustrates the correct level of the auriculotemporal nerve. No abnormality in the retromandibular region is depicted at this level. indicates the posterior margin of the mandibular ramus.