Summary Accurate pathological diagnosis is crucial for optimal management of cancer patients. For the ~100 known central nervous system (CNS) tumour entities, standardization of the diagnostic process has been shown to be particularly challenging - with substantial inter-observer variability in the histopathological diagnosis of many tumour types. We herein present the development of a comprehensive approach for DNA methylation-based CNS tumour classification across all entities and age groups, and demonstrate its application in a routine diagnostic setting. We show that availability of this method may have substantial impact on diagnostic precision compared with standard methods, resulting in a change of diagnosis in up to 12% of prospective cases. For broader accessibility we have designed a free online classifier tool (www.molecularneuropathology.org) requiring no additional onsite data processing. Our results provide a blueprint for the generation of machine learning-based tumour classifiers across other cancer entities, with the potential to fundamentally transform tumour pathology.

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28Childhood-onset craniopharyngiomas are rare embryonal malformations of low-grade

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Craniopharyngioma is a rare dysontogenetic benign tumor. Patients frequently suffer from endocrine deficiencies, sleep disturbances, and obesity due to pituitary and hypothalamic lesions. A self-assessment daytime sleepiness questionnaire (German version of the Epworth Sleepiness Scale) was used to evaluate 79 patients with childhood craniopharyngioma. Because hypothalamic lesions may explain daytime sleepiness in craniopharyngioma patients, salivary melatonin and cortisol concentrations were examined in obese and nonobese craniopharyngioma patients (n = 79), patients with hypothalamic pilocytic astrocytoma (n = 19), and control subjects (n = 30). Using a general linear model procedure analyzing the influence of body mass index (BMI) and tumor diagnosis on diurnal salivary melatonin, we found that morning salivary melatonin levels were related to BMI (by F test, P = 0.004) and tumor diagnosis (by F test, P = 0.032). Also for nighttime salivary melatonin levels significant relations with BMI (by F test, P < 0.001) and tumor diagnosis (by F test, P = 0.025) were detectable. Melatonin concentrations in saliva of craniopharyngioma patients collected at night or in the morning showed a negative correlation (night: Spearman's rho = -0.42; P = 0.001; morning: Spearman's rho = -0.31; P = 0.020) with the patient's Epworth Sleepiness Scale score. Severely obese craniopharyngioma patients and severely obese hypothalamic tumor patients had similar patterns of melatonin secretion. Differences in terms of diurnal salivary cortisol concentrations were not detectable when patient groups and controls were compared. We speculate that hypothalamic lesions might be responsible for both obesity and daytime sleepiness. As decreased nocturnal melatonin levels were associated with increased daytime sleepiness, BMI, and hypothalamic tumor diagnosis, further studies on the beneficial effects of melatonin substitution on daytime sleepiness and weight control in these patients are warranted.

Craniopharyngioma is a rare dysontogenetic benign tumor. Patients frequently suffer from endocrine deficiencies, sleep disturbances, and obesity due to pituitary and hypothalamic lesions. A self-assessment daytime sleepiness questionnaire (German version of the Epworth Sleepiness Scale) was used to evaluate 79 patients with childhood craniopharyngioma. Because hypothalamic lesions may explain daytime sleepiness in craniopharyngioma patients, salivary melatonin and cortisol concentrations were examined in obese and nonobese craniopharyngioma patients (n = 79), patients with hypothalamic pilocytic astrocytoma (n = 19), and control subjects (n = 30). Using a general linear model procedure analyzing the influence of body mass index (BMI) and tumor diagnosis on diurnal salivary melatonin, we found that morning salivary melatonin levels were related to BMI (by F test, P = 0.004) and tumor diagnosis (by F test, P = 0.032). Also for nighttime salivary melatonin levels significant relations with BMI (by F test, P < 0.001) and tumor diagnosis (by F test, P = 0.025) were detectable. Melatonin concentrations in saliva of craniopharyngioma patients collected at night or in the morning showed a negative correlation (night: Spearman's rho = -0.42; P = 0.001; morning: Spearman's rho = -0.31; P = 0.020) with the patient's Epworth Sleepiness Scale score. Severely obese craniopharyngioma patients and severely obese hypothalamic tumor patients had similar patterns of melatonin secretion. Differences in terms of diurnal salivary cortisol concentrations were not detectable when patient groups and controls were compared. We speculate that hypothalamic lesions might be responsible for both obesity and daytime sleepiness. As decreased nocturnal melatonin levels were associated with increased daytime sleepiness, BMI, and hypothalamic tumor diagnosis, further studies on the beneficial effects of melatonin substitution on daytime sleepiness and weight control in these patients are warranted.

Craniopharyngiomas are rare histologically benign but clinically challenging neoplasms. To obtain further information on the molecular genetics and biology of craniopharyngiomas, we analyzed a cohort of 121 adamantinomatous and 16 papillary craniopharyngiomas (ACP, PCP). We extracted DNA from formalin-fixed paraffin-embedded tissue and determined mutational status of CTNNB1, BRAF, and DDX3X by Sanger sequencing, next generation panel sequencing, and pyrosequencing. Sixteen craniopharyngiomas were further analyzed by molecular inversion profiling (MIP); 76.1% of the ACP were mutated in exon 3 of CTNNB1 encoding for β-catenin and there was a trend towards a worse event-free survival in cases mutated at Thr41. Next generation panel sequencing of 26 ACP did not detect any recurrent mutations other than CTNNB1 mutations. BRAF V600E mutations were found in 94% of the PCP, but not in ACP. GISTIC analysis of MIP data showed no significant larger chromosomal aberrations but a fraction of ACP showed recurrent focal gains of chromosomal material, other cases showed loss in the chromosomal region Xq28, and a third group and the PCP had stable genomes. In conclusion, the crucial pathogenetic event appears to be WNT activation in ACP, whereas it appears to be activation of the Ras/Raf/MEK/ERK pathway by BRAF V600E mutations in PCP.

Hypothalamic obesity is an intractable form of obesity syndrome that was initially described in patients with hypothalamic tumours and surgical damage. However, this definition is now expanded to include obesity developing after a variety of insults, including intracranial infections, infiltrations, trauma, vascular problems and hydrocephalus, in addition to acquired or congenital functional defects in central energy homeostasis in children with the so-called common obesity. The pathogenetic mechanisms underlying hypothalamic obesity are complex and multifactorial. Weight gain results from damage to the ventromedial hypothalamus, which leads, variously, to hyperphagia, a low-resting metabolic rate; autonomic imbalance; growth hormone-, gonadotropins and thyroid-stimulating hormone deficiency; hypomobility; and insomnia. Hypothalamic obesity did not receive enough attention, as evidenced by rarity of studies in this group of patients. A satellite symposium was held during the European Congress of Obesity in May 2011, in Istanbul, Turkey, to discuss recent developments and concepts regarding pathophysiology and management of hypothalamic obesity in children. An international group of leading researchers presented certain aspects of the problem. This paper summarizes the highlights of this symposium. Understanding the central role of the hypothalamus in the regulation of feeding and energy metabolism will help us gain insights into the pathogenesis and management of common obesity.