ESPE Abstracts

Unexplained or idiopathic pituitary stalk thickening (PST) often represents a diagnostic conundrum in children and young people. PST can be the first sign of an occult malignancy (>40% of the known aetiologies are neoplastic, particularly when associated with AVP-deficiency), but it can also reflect inflammatory, autoimmune or infectious processes, as well as congenital defects. What is perceived at PST on neuroimaging could even simply represent the upper end of the physiological variations in size of the pituitary stalk. Precise normative size stalk criteria for children are lacking, hence the size definition for PST is arbitrary. The interpretation of PST requires neuroradiology expertise and the size criteria should never be used in isolation for decision making. Between 2014 and 2019, a multidisciplinary, expert national guideline development group in the UK systematically developed a management flowchart and clinical practice guideline to inform specialist care and improve outcomes in children and young people (aged <19 years) with idiopathic PST, AVP-deficiency, or both. All such cases require dynamic pituitary function testing, specialist pituitary imaging, measurement of serum β-human chorionic gonadotropin and alpha-fetoprotein concentrations, chest x-ray, abdominal ultrasonography, optometry, and skeletal survey. Stalk thickening of 4 mm or more at the optic chiasm, 3 mm or more at pituitary insertion, or both, is potentially pathological, particularly if an endocrinopathy, visual impairment, or other neuroimaging abnormalities coexists. Smaller stalks (i.e. 3 mm or more at the optic chiasm, 2 mm or more at pituitary insertion) could also reflect pathology if other risk factors are present in the same patient. In cases where the above first line investigations do not pinpoint toward a specific aetiology, there is a role for a watch and wait strategy with careful surveillance, or for second line investigations such as cerebrospinal fluid tumour markers, whole-body imaging, or even consideration for a stalk biopsy (in rare cases), which need to be assessed on a case by case basis. Conversely, some stable cases might be discharged after some years of surveillance. The talk will provide a summary of the available evidence and some guidance for the clinicians facing this difficult clinical scenario.