The WHO classification of pituitary tumours: a combined neurosurgical and neuropathological view

Abstract

Ambitious efforts were undertaken to elucidate the molecular pathogenesis of pituitary adenomas, and tumorigenesis has reached a new level of complexity. The identification of specific signalling pathways as well as molecular genetic alterations of tumour suppressor genes and oncogenes led to a novel classification system of pituitary tumours, which is published by the World Health Organization (WHO) in 2004 [2] and now comprehensively reviewed by Mubarak Al-Shraim and Sylvia L. Asa in the current issue of Acta Neuropathologica. From a clinician’s point of view, molecular and histological grading patterns have an increasing impact onto the development of specific treatment strategies but should also address our long-standing bed-side experience. In this respect, the new 2004 WHO classification of pituitary tumours is challenging but requires interpretation. Despite the progress achieved in the pathogenesis of tumours of the sellar region, there is still no reliable marker predicting the biological behaviour of pituitary adenomas, i.e. invasiveness and recurrency. Therefore, diagnostic procedures and surgical or pharmacological treatment options have to follow well-established paradigms: