Management of children and young people with idiopathic pituitary stalk thickening, central diabetes insipidus, or both: a national clinical practice consensus guideline.

Unexplained or idiopathic pituitary stalk thickening or central diabetes insipidus not only harbours rare occult malignancies in 40% of cases but can also reflect benign congenital defects. 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 pituitary stalk thickening, central diabetes insipidus, or both. All such cases of idiopathic pituitary stalk thickening and central diabetes insipidus 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 for occult disease. 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 or visual impairment coexists. In this guideline, we define the role of surveillance, cerebrospinal fluid tumour markers, whole-body imaging, indications, timing and risks of stalk biopsy, and criteria for discharge. We encourage a registry of outcomes to validate the systematic approach described in this guideline and research to establish typical paediatric stalk sizes and the possible role of novel biomarkers, imaging techniques, or both, in diagnosis.

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Declaration of interests IK-A has been a member of the National Health Service England Paediatric Neurosciences Clinical Reference Group from 2013 onwards, member of Council of the Society of British Neurological Surgeons from 2018 onwards, and was chairman of the British Paediatric Neurosurgical Group from 2016 to 2018. TJ reports grants from Brain Tumour Charity, Children with Cancer UK, Cancer Research UK, Great Ormond Street Hospital Children's Charity, Olivia Hodson Cancer Fund, and National Institute of Health Research; and personal fees from Bayer, outside of the submitted work. TJ is also a director and shareholder in Repath and Neuropath; the company secretary at Repath; the editor in chief of Neuropathology and Applied Neurobiology; and the lead for the childhood solid tumour domain Genomes Clinical Interpretation Partnership for Genomes England and the 100 000 genomes projects. HAS is chair of the Project Board for all eight paediatric endocrine tumours in simultaneous development; Project Board Lead for pituitary adenomas, craniopharyngiomas, and idiopathic PST, CDI, or both; responsible for raising grants to fund wider endeavour; initiator and founder of group with wider involvement across all guidelines; non-renumerated, voluntary trustee, founder, and chair of Success Charity–Life After Cure (RCN 1188298); and is a stakeholder in this guideline and donated (like other charity stakeholders Association of Multiple Endocrine Neoplastic Disorders, Pituitary Foundation, BSPED, British Neurological Surgeons, RCPCH, and CCLG) between £1000 and £3000 either in kind or in a restricted grant to the CCLG charity to support its administrative expenses only for this and seven other endocrine tumour childhood guidelines. All other authors declare no competing interests.