CT Case 065
A 25-year-old lady presents to the ED with several weeks of blurred vision and diplopia.
She has no known previous medical history.
Eye movements are painful on lateral gaze and she has an incomplete right third nerve palsy.
A CT scan of the brain is performed
Describe and interpret the CT images
CT shows a large sellar, para-sellar and supra-sellar lesion expanding and eroding sphenoid sinus with tumour bulging into the nasopharynx and invading cavernous sinuses.
This suggests an aggressive giant pituitary macroadenoma with invasion of surrounding structures.
Subsequently an MRI brain was performed
MRI scan interpretation
MRI is the investigation modality of choice as it can show involvement of cavernous sinuses, encasement of ICAs and identify extension into soft tissues.
When a sellar mass is identified, another differential to consider is a craniopharyngioma in which the pituitary can be seen separate to the lesion.
Clinical Pearls
Pituitary adenomas are the fourth most common intracranial tumour after gliomas, meningiomas and schwannomas.
They most commonly affect people in their 30s and 40s.
These tumours can vary in size and behaviour.
Those that produce hormones are called functioning adenomas, while those that do not are called non-functioning adenomas.
Tumours small than 10mm are classified as microadenomas, and often secrete anterior pituitary hormones.
Adenomas larger than 10mm are called macroadenomas, usually, but not always, they do not secrete hormones. Macroadenomas are often discovered because they produce symptoms by “mass effect,” compressing nearby brain or cranial nerve structures, this often presents with visual change and headache.
A tumour greater than 40mm is classified as a giant adenoma.
A third of functioning pituitary adenomas (FPAs) are prolactinomas, as in this case.
An increase in plasma prolactin levels induces amenorrhea/oligomenorrhea, galactorrhea, infertility and impotence.
On further questioning of this patient, she describes oligomenorrhoea. This patient’s prolactin level was 10,000 mIU/L (normal range 100-500mIU/L), consistent with a functioning pituitary adenoma.
Most pituitary adenoma, other than prolactinomas are treated by surgery (usually transsphenoidal), however the first treatment choice for most prolactinomas is medication, in this case Cabergoline.
This is a dopamine agonist which acts to reduce the size of the tumour, and has an endocrinological remission rate of 70-90%. Surgical management is reserved for patients with optic chiasm progression and progressive visual deficit as in this case, or for patients with haemorrhagic tumours or intolerance of medical therapy.
References
- Gibbs M. Neuroimaging Cases 006. LITFL
- Nickson C. Third Cranial Nerve Lesions. CCC
- Oki Y. Medical management of functioning pituitary adenoma: an update. Neurol Med Chir (Tokyo). 2014;54(12):958-65.
TOP 100 CT SERIES
Sydney-based Emergency Physician (MBBS, FACEM) working at Liverpool Hospital. Passionate about education, trainees and travel. Special interests include radiology, orthopaedics and trauma. Creator of the Sydney Emergency XRay interpretation day (SEXI).
Provisional fellow in emergency radiology, Liverpool hospital, Sydney. Other areas of interest include paediatric and cardiac imaging.
Emergency Medicine Education Fellow at Liverpool Hospital NSW. MBBS (Hons) Monash University. Interests in indigenous health and medical education. When not in the emergency department, can most likely be found running up some mountain training for the next ultramarathon.
Dr Leon Lam FRANZCR MBBS BSci(Med). Clinical Radiologist and Senior Staff Specialist at Liverpool Hospital, Sydney