SAT-445 Pituitary Stalk Lesions: Difficult to Identify with Varied Clinical, Biochemical, and Radiological Presentations

Background: Pituitary stalk connects the hypothalamus and pituitary. It measures 1.9-3.5mm with a mean value of around 1.5 mm. Detection of such lesions upon MR imaging therefore requires an experienced neuro-radiologist. Etiologies can include autoimmune causes like lymphocytic hypophysitis or granulomatous disorders such as sarcoidosis, neoplastic lesions like germinomas and others. These conditions are relatively rare with poorly understood clinical presentations and can be very challenging diagnostically. Objectives: To study the clinical presentation, imaging and endocrine abnormalities in patients presenting with apparent pituitary stalk lesions to a tertiary endocrine clinic in the UK. Materials and methods: We conducted a retrospective case notes review of patients referred with pituitary stalk lesions who attended the Joint Pituitary clinic between 2010 and 2018.Results: 73 cases with Pituitary stalk lesion were identified by initial MRI generalist radiologist reporting. 60 patients were diagnosed as Rathke’s cleft cyst by the pituitary MDT. The other 13 cases (7 males) had median age of 50 (range 32-85) years at diagnosis. Median size of Pituitary stalk lesions on MRI scans was 7 mm (range 2mm to 30mm). Five patients (38%) had associated pituitary gland abnormalities (3 bulky pituitary, 2 adenomas). Five cases (38%) presented with polyuria and polydypsia, 2 patients (15%) with fatigue and 1 patient with galactorrhea as the main symptoms while 4 cases (31%) were identified during MR scans done to evaluate headaches. 11 (85%) cases had an endocrine abnormality. Eight patients (62%) were identified to have cranial diabetes insipidus (CDI) on its own or in combination with other endocrine anomalies which included three cases (23%) with panhypopituitarism and three other cases with partial anterior pituitary hypofunction. Of the ten patients who had an IST/GST performed, nine (90%) had Growth hormone deficiency and four (30%) had cortisol deficiency. Three patients (23%) had only partial anterior pituitary hypofunction without CDI. Four cases (30%) had hyperprolactinemia in combination with cranial diabetes insipidus or partial anterior pituitary hypofunction. Two patients(15%) had biopsies of the lesions (one germinoma and one granular cell lesion). On radiological grounds, one patient was thought to have a meningioma, two lymphocytic hypophysitis and one felt to have an epidermoid cyst. Conclusions: Most Pituitary stalk lesions referred to the pituitary MDT are actually misreported Rathkes cleft cysts. Pituitary stalk lesions can present with multiple endocrine abnormalities, the commonest being Growth hormone deficiency and cranial diabetes insipidus. A high index of suspicion is needed during radiological evaluation of such presentations. An IST/GST should be performed in all cases of pituitary stalk lesions.