Endocrine Abstracts

Background: Pituitary metastasis is a rare but life-threatening condition. Patients typically present with visual symptoms, AVP deficiency (diabetes insipidus), and hypopituitarism. We report a couple of cases of pituitary metastasis with varied presentations.

Case 1: A 52-year-old male presented with frontal headaches, polydipsia, visual disturbances, and extreme fatigue. Biochemistry was consistent with hypopituitarism including AVP deficiency; Pituitary MRI revealed a suprasellar pituitary lesion (1.7x1.6x1.4 cm), compressing the optic chiasm. He was started on hydrocortisone, levothyroxine, and desmopressin. Within two weeks, he presented with worsening headaches and confusion. A repeat MRI showed a heterogeneous lesion with a distorted contour & 1 cm size increase. CT CAP revealed a 5 cm lung mass, confirmed on histology as non-small cell lung cancer. He underwent pituitary debulking surgery, followed by chemotherapy. Histology confirmed pituitary metastasis from lung primary. The prognosis remains poor due to lack of treatment response.

Case 2: A 61-year-old female with a recent diagnosis of non-small cell lung cancer presented with left arm weakness. A CT head showed cerebral metastasis. She was hypotensive and hyponatraemic, with blood tests confirming hypopituitarism but no overt evidence of AVP deficiency. She was started on hydrocortisone and levothyroxine. An MRI of the pituitary confirmed pituitary metastasis characterized by an intrasellar focal signal abnormality measuring 11 x 14 x 14 mm with a very thin surrounding layer of residual pituitary tissue. An MDT-led decision was made to start her on palliative radiotherapy.

Learning points: 1. Pituitary metastasis should be considered as a differential diagnosis if AVP deficiency is part of the initial clinical presentation. 2. Cancer patients with extreme fatigue should be screened for hypopituitarism and have a low threshold for pituitary scanning to rule out pituitary metastasis. 3. Pituitary metastasis bears poor prognosis and can have variable degree of hormonal deficiencies, with or without AVP deficiency.