Delayed diagnosis of cranial neuropathies from perineural spread of skin cancer

Perineural spread (PNS) to cranial nerves (CNs) by cutaneous malignancies is difficult to diagnose given the indolent course and often late or absent findings on brain imaging. A 68-year-old white man with multiple cranial neuropathies secondary to PNS by squamous cell carcinoma had negative high-quality neuroimaging for 5.25 years. He first developed left facial numbness, followed 39 months later by a left CN VI palsy. Subsequent examinations over 2 years showed involvement of left seventh, right trigeminal V1–V3, and right sixth, and bilateral third nerve palsies. Repeat high-quality brain magnetic resonance imaging (MRIs) during this time showed no identifiable CNs abnormality. Full body positron emission tomography imaging and cerebrospinal fluid studies were normal. 5.25 years after initial sensory symptom onset, MRI showed new enhancement along the right mandibular branch of the trigeminal nerve with foramen ovale widening. Autopsy showed squamous cell carcinoma within both CNs sixth. A long interval to diagnosis of PNS is associated with high morbidity, emphasizing the need for earlier methods of detection when clinical suspicion is high.