Endocrine Abstracts

Common non-specific symptoms like fatigue can occasionally point towards a rare significant pathology. We report a similar case in which investigations for subtle symptoms revealed a serious unexpected diagnosis. A 76 year-old man presented to his GP for new onset mild fatigue. He had an underlying prostate cancer with no known metastases, treated only with hormonal therapy. This was under surveillance with urology team. GP sent off blood tests which showed a very low random serum cortisol (28nmol/L). Hence an urgent endocrine review and short Synacthen test (SST) was organised. SST showed secondary adrenal insufficiency. Baseline 9am ACTH = 41ng/L (>50ng/L) Baseline 9am cortisol = 116nmol/L (>420nmol/L) 60 min cortisol after Synacthen injection: 471nmol/L (>420nmol/L) The remaining pituitary hormonal profile showed secondary hypothyroidism (TSH=1.34mIU/L, T4=5.3mcg/dL) and raised prolactin (565 mcg/L). He was started on oral hydrocortisone after the above results whilst awaiting endocrine appointment. By the time patient attended the endocrine clinic in 3 weeks he was noted to be wearing a homemade eye patch over his left eye. On questioning he reported new diplopia and visual impairment for which he had consulted private optician who referred him to ophthalmologist. On examination there was with left oculomotor nerve palsy and bitemporal hemianopia. He was admitted in hospital from endocrine clinic and an urgent pituitary MRI was organised. This revealed a large sellar mass (1.8x2.2x3cm) with extension into the cavernous and sphenoid sinuses. These findings were consistent with a diagnosis of pituitary macroadenoma causing chiasm compression and partial hypopituitarism. The final impression was non-functional pituitary macroadenoma causing compressive symptoms. He was urgently referred for trans-sphenoidal surgery. Trans-sphenoidal surgery proved to be complex leaving residual tumour and was complicated with post-operative diabetes insipidus with persistent visual impairment. Histology of pituitary tumour showed metastatic adenocarcinoma of prostatic origin. The patient later received radiotherapy. Unfortunately, surveillance imaging confirmed disease progression with enlargement of the remnant lesion and more extensive involvement of adjacent structures. Currently the patient is on palliative radiotherapy with full pituitary hormone replacement. Fatigue is a nonspecific common symptom. Low random cortisol is usually not expedited as an urgent test however in context of secondary hypothyroidism it should prompt urgent pituitary imaging especially in patients with history of prostate cancer. There have been only a handful of cases of prostate metastasis in the pituitary gland. This case reminds about rare metastatic presentations in pituitary gland.