Endocrine Abstracts

The commonest cause of acquired hypopituitarism is a benign pituitary adenoma. However, in patients with non-pituitary malignancy different diagnoses need to be considered. We describe three oncology patients presenting with hypopituitarism and/or a pituitary mass where the cause was related either to malignant disease or its treatment.

Case 1: A 56-year-old man with known metastatic melanoma presented with increasing lethargy. Investigation showed a large heterogeneous mass in the suprasellar region with a displaced normal enhancing pituitary gland. The mass was thought to be melanoma metastasis, and showed significant reduction in size (more than 70%) following treatment with vemurafenib, a B-Raf kinase inhibitor.

Case 2: A 62-year-old man with known metastatic melanoma presented with fatigue and was found to have hypopituitarism (Ft₄ – 5.0 pmol/l, TSH – 0.15 mIU/l, Cortisol – 13 nmol/l, Prolactin – 121 mIU/l, Testosterone – <0.4 nmol/l, LH – 1.5 IU/l, FSH – 2.5 IU/l). MRI scan of the pituitary was normal. The patient was on Ipilimumab (human monoclonal antibody directed against cytotoxic T lymphocyte antigen 4 (CTLA-4)), which has been reported to cause hypopituitarism secondary to hypophysitis (Hodi et al. New England Journal of Medicine 363 711, 2010).

Case 3: A 73-year-old woman with diffuse large B cell non-Hodgkin lymphoma (DLBCL) presented with third nerve palsy and lethargy. MRI showed a large pituitary lesion thought to be either lymphoma or a pituitary macroadenoma. The pituitary lesion showed near complete shrinkage following three cycles of CHOP-R chemotherapy.

These three cases illustrate that patients with non-pituitary malignancy presenting with fatigue should be investigated for hypopituitarism. In oncology patients, the causes of hypopituitarism may include metastasis and side effects from treatment of the primary malignancy including hypophysitis.