The new World Health Organization classification of haematopoietic and lymphoid tumours: a dermatopathological perspective.

The World Health Organization (WHO) has published a new consensus classification of tumours of haematopoietic and lymphoid tissue, based on recognizable disease entities defined by clinical and scientific criteria. The WHO does not support the use of stand-alone organ-related classifications, such as for skin. The Royal College of Pathologists (London) has adopted the WHO classification in its minimum dataset for the histopathological reporting of lymphoma and this will be used in the National Health Service Skin Cancer Dataset. The purpose of this review is to highlight the principal primary and secondary cutaneous haematopoietic and lymphoid tumours that are defined in the WHO classification. The review also discusses selected problematical areas in the WHO classification relevant to the skin and contains suggestions to encourage a unified approach in the use of the WHO coded summary. These represent an attempt to facilitate future progress and research in the field of cutaneous lymphoma. They are perceived as possible building-blocks for wider discussion and not as alterations to the classification. The WHO classification has been compared with a road map that indicates directions for future clinical and scientific research.