Endocrine Abstracts

Case Report: A 65-year-old woman presented with a 5 months history of severe headache, fatigue, nausea, vomiting, polyuria, and polydipsia. Biochemical investigations confirmed panhypopituitarism, including secondary adrenal insufficiency (cortisol<28 nmol/L, ACTH <5 ng/L) with Arginine Vasopressin Deficiency (AVD). Pituitary hormone replacement therapy was commenced (excluding growth hormone replacement). MRI demonstrated a bilobed sellar mass with suprasellar extension, with a partial bitemporal hemianopia observed on formal visual field assessments. The presence of profound hypopituitarism with AVD led us to consider metastatic disease as the most likely diagnosis with inflammatory conditions in the differential. FDG PET scan revealed a 4cm lung mass suspicious for primary lung cancer with multiple FDG-avid lymph nodes, including supraclavicular nodes. Biopsy of a left supraclavicular lymph node confirmed metastatic lung adenocarcinoma with an EGFR exon 19 deletion.

Treatment: She was treated with Osimertinib, a third-generation EGFR-Tyrosine Kinase Inhibitor. Three months following Osimertinib commencement, she experienced resolution of headaches with associated nausea. A marked reduction in the dimensions of the sella mass with resolution in the suprasellar component was visualised on repeat MRI. There was a retraction within the pituitary gland. The optic chiasm and pre-chiasmatic nerves were no longer compressed. These findings corroborated with ophthalmic assessments where normal visual fields were observed. Despite the significant radiological and ophthalmic improvements, hypopituitarism persisted for which she remained on pituitary hormone replacement.

Conclusion: Pituitary metastasis is rare, with lung and breast malignancies the commonest causes. Treatment approaches include surgery or radiotherapy focused on mitigating visual complications. This case highlights the importance of tissue diagnosis, enabling the use of targeted therapy, including Osimertinib, which has led to regression of the metastatic disease improving symptoms and visual function.