Pineal Physiology and Pathophysiology, Including Pineal Tumours

Pineal physiology and tumours are briefly summarized in this chapter. The main pineal hormone melatonin is secreted at night and entrains endogenous rhythms to the environment. Melatonin deficiency has been associated to sleeping disorders, behavioural problems, and abnormal puberty, while its excess has been described in hypogonadotropic hypogonadism. Outcome after diagnosis of a pineal tumour have improved in the last decades after better understanding of the natural history of these tumours, neurosurgical experience, use of chemotherapy, and current irradiation techniques. The low prevalence of these pineal tumours has prevented any large prospective multicentre international studies aimed at identifying optimal management. The most recent World Health Organization (WHO) classification of central nervous system tumours published in 2016, defines molecular parameters as well as histology to classify these tumour entities, formulating a molecular diagnosis for these tumours.