Acute shrinkage of a giant prolactinoma, masquerading as an erosive skull base tumour, with cabergoline.

A 27-year-old Chinese male presented with a 2-year history of headache and a right temporal field defect. A magnetic resonance imaging (MRI) scan revealed a 5cm tumour in the sphenoid with bilateral cavernous sinus extension and posterior extension to the clivus (Figure 1A). This was reported as an erosive skull base tumour and he was referred to neurosurgery. His serum prolactin was measured at 283 909mU/l (normal range 45–375mU/l), confirming a giant prolactinoma. After a single dose of 250mcg cabergoline, there was an improvement in his visual field, tumour reduction and fall in prolactin to 57 539mU/l (Figure 1B). An increased dose of 250mcg twice weekly resulted in further tumour shrinkage, a fall in prolactin and normalization of his visual fields (Figure 1C and D). This case highlights the importance of measurement of serum prolactin in the evaluation of potential skull base tumours and the rapid shrinkage of giant prolactinomas with primary medical therapy obviating the need for surgery. Photographs and text from: S. Dash, A.K. Annamalai and H.L. Simpson, Institute of Metabolic Science, Wolfson Diabetes and Endocrine Clinic, Addenbrooke’s Hospital, Cambridge University NHS Trust, Hills Road, Cambridge CB2 0QQ, UK; N. Sarkies, Department of Opthalmology, Cambridge University NHS Trust, Hills Road, Cambridge CB2 0QQ, UK; N.M. Antoun, Department of Radiology, Cambridge University NHS Trust, Hills Road, Cambridge CB2 0QQ, UK; R. Mannion, Department of Neurosciences and Department of Neurosurgery, Cambridge University NHS Trust, Hills Road, Cambridge CB2 0QQ, UK. email: [email protected]