Editorial

Abstract

Unusually, in this issue we publish four papers dealing with round cell tumours. Two are concerned with lymphoma1,2 (in cattle and a dog) and two with histiocytic cells3,4 (in a dog and a cat). In the past, the classification of these tumours would have been difficult. Now that markers are available to demonstrate the immunophenotype of the tumour cells, classification has become easier, at least for those with access to more sophisticated laboratories. Even so, classification remains a problem, not only in the veterinary field but also in human medicine. This is particularly true for the histiocytic tumours, which can be reactive or malignant, a difference that is often difficult to determine. An indication of the importance of histiocytic disorders in veterinary dermatology was the selection of this topic as the state of the art address in a main theme at the Fourth World Congress of Veterinary Dermatology, dealing with Dysplasia and Neoplasia. Dr Verena Affolter reviewed the current knowledge of histiocytic cells (monocytes, macrophages and dendritic cells), which are believed to arise from a common CD34 + precursor.5 In the same session, Baines et al. described the maturation states of cells in canine cutaneous histiocytoma by immunophenotyping cells from excised tumours using flow cytometry.6 They showed that the clinical stages of the tumours were characterized by neoplastic Langerhans’ cells at different stages of maturation. The stages present during progression and regression reflected the natural life cycle of normal Langerhans’ cells. The September issue of the British Journal of Dermatology also contained two interesting cases of histiocytic disease. The editorial in that issue reviewed the current state of knowledge in the human field of the histiocytoses.7 These diseases were reclassified in 1997 into three groups:1 Langerhans’ cell histiocytosis,2 Non-Langerhans’ cell histiocytoses, and3 Malignant histiocytoses.8 The group 2 histiocytoses present special difficulty as they involve dermal dendrocytes, a poorly understood group of factor XIIIa positive cells in which derivation from CD34 + bone marrow precursors is as yet unproven. The class 2 tumours include a variety of different clinical entities and Chu7 proposes that their clinical presentations are determined by the level of maturation of the dendrocytes involved. He suggests that the more mature cells are associated with more severe syndromes that are less responsive to treatment. It is clear that, even though immunophenotyping enables us to define the cells involved in histiocytic tumours, there is a great deal still to be learned. As is so often the case, as we learn more so we recognize how little we really understand. This is my last Editorial as Editor-in-Chief and I take the opportunity to pay credit to the many colleagues who have made the job such a pleasure for me. Special thanks are due to my co-editors, Karen Moriello and Ross Bond, who have the responsibility for receiving submissions, arranging for their review, communicating with authors and preparing accepted papers for publication. This is no small task and the quality of Veterinary Dermatology depends to a great extent on their dedication. I wish also to thank the Editorial Board and the Journal Development Advisory Chairs, Richard Anderson and Richard Harvey, who provide continuing support and advice to the editorial team, and to our translators who enable us to publish abstracts in French, German and Spanish. Finally, I would like to thank our publishers, Blackwell Science, who are lovely people to work with. Our new Editor-in-chief is Ian Mason. Ian is a former European co-editor and has a profound knowledge of all aspects of the Journal. I know that in his hands it will prosper. Thank you for taking on the job, Ian. Over to you! D. H. Lloyd