A healthy 68-year-old man presented in the emergency room with a sudden episode of headache and vomiting together with disequilibrium and crural paresis. The laboratory evaluation revealed hyponatraemia (Na+115 mEq/L). Head MRI demonstrated a giant 40×25×31 mm pituitary lesion (figures 1 and 2). Laboratory studies revealed growth hormone (GH) 0.1 ng/mL (0.06–5), follicle-stimulating hormone (FSH) 14.5 mUI/mL (0.7–11.1), luteinising hormone (LH) 1.9 mUI/mL (0.8–7.6), prolactin 23.1 ng/mL (2.5–17), low free thyroxine (fT4) 0.4 ng/mL (0.8–1.9), thyroid-stimulating hormone (TSH) 7.88 mUI/mL (0.4–4), cortisol 2.4 μg/dL (5–25), adrenocorticotropic hormone (ACTH) 9.26 pg/mL (<46), insulin-like growth factor-1 (IGF1) <25 ng/mL (69–200), testosterone <0.04 ng/mL (5.6–19) and sex hormone binding globulin (SHBG) 30 nmol/L (13–71). Figure 1 MRI Sagittal T1-weighted image showing a sellar and suprasellar tumour, remodelling the sella turcica. Note the extension of the tumour to the sphenoid sinus. Figure 2 MRI Coronal T2-weighted image illustrates the heterogeneous MR signal evolution. Note the mass effect and compression over …