Who Classification of Tumours of the Central Nervous System (4th edition)

Louis, David N., Ohgaki, Hiroko, Wiestler, Otmar D. and Cavenee, Webster K. Who Classification of Tumours of the Central Nervous System (4th edition) International Agency for Research on Cancer Lyon , 2007 . 312 Pages. Price approximately £61 ($122) (softback). ISBN 978i-92-832-2430-2 The title of this book is typically modest. It is not only a classification of tumours of the central nervous system (CNS); but an authoritative and explicit account of this group of tumours. In the recent tradition of World Health Organization's (WHO) books on tumours, coloured blue for immediate recognition, the text and illustrations have been compiled by an international team of 75 experts following a meeting of a Working Group of 25 pathologists in Heidelberg in November 2006. The book was published just over 6 months later endowing commendable immediacy to the text and bibliography. This, the fourth edition, contains a number of distinct improvements on previous editions, both in layout and content. This has been achieved without lengthening the book and the result is a user-friendly succinct manual. As with previous editions, the page of contents mirrors the sequence of tumours in the classification and each chapter has a standard format. One new feature is the clear account of the WHO's grading system, its rationale and its application. Each chapter covers a defined group of tumours and is prefaced by a succinct one-page summary. There is a standard set of headings for each type of tumour covering clinical and epidemiological aspects, imaging, histopathology, immunocytochemistry, genetics, treatment and prognosis. These features greatly facilitate navigation of the book and acquisition of information from the text. Throughout the book, the illustrations are of good quality and well integrated into the text. Graphs are clearly presented and allow the reader to grasp demographic information at a glance and to clearly appreciate, e.g. the relationships of age to TP53 mutations, epidermal growth factor receptor amplifications and prognosis in glioblastomas. Apart from the increased clarity of presentation, what is new in the fourth edition? New tumour entities are included, e.g. angiocentric glioma, papillary glioneuronal tumour and rosette-forming glioneuronal tumour of the fourth ventricle. Newly recognized histological variants include pilomyxoid astrocytoma. Both anaplastic medulloblastoma and medulloblastoma with extensive nodularity have gained recognition in the classification. Inclusion of new entities is a very important function of the WHO books. Not only does it give confidence to pathologists in diagnosing such tumours, but it also relieves some of the anxiety induced when faced with a rare and unfamiliar histological appearance. In addition to those entities mentioned above, there are some differences in classification from the third edition, most notably relating to anaplastic oligoastrocytoma. In the previous edition, necrosis was a ‘permitted’ high-grade feature, whereas this results in the diagnosis of ‘glioblastoma with oligodendroglial component’ in the fourth edition, and hence a grade IV diagnosis rather than grade III. The change in emphasis follows cited differences in prognosis between mixed tumours with and without necrosis, with the new entity carrying a better prognosis than standard glioblastoma. While some will disagree with the shift in emphasis, others will be relieved by the attempt to standardize diagnostic practice. Other changes are also apparent, e.g. within the atypical teratoid/rhabdoid section, mention of the INI-1 locus in the genetics section in the third edition has been expanded to include immunohistochemistry in the fourth edition. The difference between a great book on tumours and a good book could be defined in terms of its universal appeal. It may be too early to judge the fourth edition in these terms for the wider community of neurosurgeons, neurologists and basic neuroscientists, but some evaluation can be made of its appeal to trainees in neuropathology. From the perspective of a trainee in neuropathology, reviewing the fourth edition was time well spent from a learning perspective, and as a means of grasping the changes in tumour diagnostic practice that have occurred in the last seven years since the previous edition was published. In terms of the book's position in the market, the fourth edition is unique in its clear-targeted and succinct style of presentation of tumours of the CNS. It may have a small target audience in terms of medicine as a whole, but it will be of universal appeal in neuro-oncology and will most certainly form the main basis for diagnosis by Multidisciplinary Teams managing patients with tumours of the CNS. Larger books, such the most recent AFIP Fascicle 7 (series IV) Tumors of the Central Nervous System by Peter Burger and Bernd Scheithauer that is similarly priced, may provide more detailed information about tumours of the CNS and will almost certainly be used in conjunction with the fourth edition of the WHO classification.