This paper presents a case of an isolated pituitary fossa metastasis on a background of a previously treated tonsillar squamous cell carcinoma.

A 64-year-old male, diagnosed with a primary p16-negative squamous cell carcinoma in the right tonsil, was treated with a course of chemoradiotherapy with curative intent. Positron emission tomography/computed tomography, performed at six months post-treatment, revealed a good local response and no distant metastases. The patient was placed on routine follow up at two-monthly intervals. Two months into follow up, he presented with a right-sided oculomotor nerve palsy and partial Horner's syndrome. Imaging and biopsy revealed a pituitary fossa metastasis (p16-negative squamous cell carcinoma), and a further positron emission tomography/computed tomography visualised this lesion. He was deemed unsuitable for further intervention and underwent palliative radiotherapy for symptom control.

This case represents the first reported isolated pituitary fossa metastasis from a tonsillar squamous cell carcinoma. A high degree of clinical suspicion is recommended, along with a low threshold for biopsy and a cautioned use of positron emission tomography/computed tomography, when investigating such patients.