Introduction: Metastatic lesion in the pituitary is a rare condition with most of them being asymptomatic. Breast cancer is the most frequent primary location and the overall prognosis is poor. We describe the case of a lady with this condition, who presented to our unit with bitemporal hemianopia.
Case: A 65 year old lady with history of breast cancer (surgical excision with chemoradiotherapy 4 years ago, HER2 negative, currently in remission) presented with bitemporal hemianopia. Endocrine testing showed hypocortisolism and secondary hypothyroidism and commenced on replacement therapy. MR Pituitary showed a pituitary lesion which was radiologically consistent with adenoma, but also revealed a posterior fossa lesion. There was significant pressure on optic chiasm which accounted for her visual field loss. Whole body imaging showed lesions in brain and lungs consistent with metastatic deposits. She underwent sellar decompression to protect her vision and is undergoing chemotherapy.
Discussion: Metastatic pituitary deposits are estimated to be around 1.8% of surgically resected pituitary lesions and they remain a rare entity. Upto 3.6% of all intracranial mets are estimated to be in the pituitary. About a quarter manifest as Diabetes insipidus and panhypopituitarism is found in a quarter as well. Most cases involve the posterior pituitary and the blood supply to this area derived from systemic circulation has been proposed to play a role. Similar to our case, incidence was 9.3 times more frequent with breast cancer, followed by lung, thyroid and renal cell cancer. Approaches to treatment have included surgery, chemotherapy, radiotherapy, radiosurgery and hormonotherapy and all modalities carry risk of panhypopitutarism. Prognosis remains poor with an estimated survival of 13.6 months from diagnosis of the Pituitary metastasis. A high degree of suspicion in cancer patients showing extreme lethargy or other symptoms of hypopituitarism might help earlier diagnosis and treatment.