Joan Guitart

Abstract We herein present an overview of the upcoming 5 th edition of the World Health Organization Classification of Haematolymphoid Tumours focussing on lymphoid neoplasms. Myeloid and histiocytic neoplasms will be presented in a separate accompanying article. Besides listing the entities of the classification, we highlight and explain changes from the revised 4 th edition. These include reorganization of entities by a hierarchical system as is adopted throughout the 5 th edition of the WHO classification of tumours of all organ systems, modification of nomenclature for some entities, revision of diagnostic criteria or subtypes, deletion of certain entities, and introduction of new entities, as well as inclusion of tumour-like lesions, mesenchymal lesions specific to lymph node and spleen, and germline predisposition syndromes associated with the lymphoid neoplasms.

Mycosis fungoides (MF) and Sézary syndrome (SS), the major forms of cutaneous T-cell lymphoma, have unique characteristics that distinguish them from other types of non-Hodgkin's lymphomas. Clinical trials in MF/SS have suffered from a lack of standardization in evaluation, staging, assessment, end points, and response criteria. Recently defined criteria for the diagnosis of early MF, guidelines for initial evaluation, and revised staging and classification criteria for MF and SS now offer the potential for uniform staging of patients enrolled in clinical trials for MF/SS. This article presents consensus recommendations for the general conduct of clinical trials of patients with MF/SS as well as methods for standardized assessment of potential disease manifestations in skin, lymph nodes, blood, and visceral organs, and definition of end points and response criteria. These guidelines should facilitate collaboration among investigators and collation of data from sponsor-generated or investigator-initiated clinical trials involving patients with MF or SS.

Although the clinical and pathologic diagnosis of some melanomas is clear-cut, there are many histopathologic simulators of melanoma that pose problems. Over-diagnosis of melanoma can lead to inappropriate therapy and psychologic burdens, whereas under-diagnosis can lead to inadequate treatment of a deadly cancer. We used existing data on DNA copy number alterations in melanoma to assemble panels of fluorescence in situ hybridization (FISH) probes suitable for the analysis of paraffin-embedded tissue. Using FISH data from a training set of 301 tumors, we established a discriminatory algorithm and validated it on an independent set of 169 unequivocal nevi and melanomas as well as 27 cases with ambiguous pathology, for which we had long-term follow-up data. An algorithm-using signal counts from a combination of 4 probes targeting chromosome 6p25, 6 centromere, 6q23, and 11q13 provided the highest diagnostic discrimination. This algorithm correctly classified melanoma with 86.7% sensitivity and 95.4% specificity in the validation cohort. The test also correctly identified as melanoma all 6 of 6 cases with ambiguous pathology that later metastasized. There was a significant difference in the metastasis free survival between test-positive and negative cases with ambiguous pathology (P=0.003). Sufficient chromosomal alterations are present in melanoma that a limited panel of FISH probes can distinguish most melanomas from most nevi, providing useful diagnostic information in cases that cannot be classified reliably by current methods. As a diagnostic aid to traditional histologic evaluation, this assay can have significant clinical impact and improve classification of melanocytic neoplasms with conflicting morphologic criteria.

Primary cutaneous CD30(+) lymphoproliferative disorders (CD30(+) LPDs) are the second most common form of cutaneous T-cell lymphomas and include lymphomatoid papulosis and primary cutaneous anaplastic large-cell lymphoma. Despite the anaplastic cytomorphology of tumor cells that suggest an aggressive course, CD30(+) LPDs are characterized by an excellent prognosis. Although a broad spectrum of therapeutic strategies has been reported, these have been limited mostly to small retrospective cohort series or case reports, and only very few prospective controlled or multicenter studies have been performed, which results in a low level of evidence for most therapies. The response rates to treatment, recurrence rates, and outcome have not been analyzed in a systematic review. Moreover, international guidelines for staging and treatment of CD30(+) LPDs have not yet been presented. Based on a literature analysis and discussions, recommendations were elaborated by a multidisciplinary expert panel of the Cutaneous Lymphoma Task Force of the European Organization for Research and Treatment of Cancer, the International Society for Cutaneous Lymphomas, and the United States Cutaneous Lymphoma Consortium. The recommendations represent the state-of-the-art management of CD30(+) LPDs and include definitions for clinical endpoints as well as response criteria for future clinical trials in CD30(+) LPDs.