Endocrine Abstracts

History: A 63 year old female presented with nausea, vomiting and loss of balance. She had no other symptoms. An MRI of the brain revealed a large incidental pituitary lesion occupying both the sella and suprasellar region, causing distortion of the optic chiasm and tracts. She had no headache, visual disturbance, tiredness, thirst or daytime frequency although she had long standing nocturia.

Examination: Visual fields showed mild bitemporal desaturation to red pin.

Investigations and treatment: FT4 6.3;TSH 0.52; cortisol 143; PRL 2034; LH 3.3; FSH 8.9; IGF-1 4.29 (12.2–35.0); sodium 139; serum osmo 291 Hydrocortisone, thyroxine and cabergoline were commenced and she underwent surgery as there was no change in tumour size at 3 months, even in the presence of a suppressed prolactin.

Desmopressin was started postoperatively and cabergoline stopped.

Histology: Granular cell tumour (GCT); faint focal immuno-reactivity with S100; stains for GFAPand chromogranin negative; MIBI labelling index approximately 2%.

Discussion: Although rare, GCTs are the most frequently occurring tumours of the neurohypophysis and pituitary stalk. They are slow growing, benign tumours (WHO grade 1 in the current classification of tumours of the CNS) thought to arise from granular cell tumourets or pituicytes in the neurohypophysis, and consequently, believed to be a form of glioma. They commonly affect older persons, and the majority are incidentally found and clinically asymptomatic. GCTs frequently compress and compromise the functions of the pituitary, hypothalamus and optic chiasm, and often mimic features of pituitary adenomas. Less commonly, GCTs are associated with dementia, Parkinson's disease, obstructive hydrocephalus and intraventricular haemorrhage. Diagnosis is confirmed by histology. Immunohistochemical studies have shown variable staining patterns, and diagnosis is primarily based on morphology.

Complete surgical removal is usually curative, but subtotal resection is associated with recurrence, necessitating radiotherapy. The rarity of this tumour makes it difficult to predict long-term outcomes.