Welcome

Welcome to the Joint CSHP-EA4HP-SH Workshop 2024! The workshop is organized by a partnership of the Chinese Society for Hematopathology (CSHP), European Association for Haematopathology (EA4HP), and Society for Hematopathology (SH). The Joint Workshop will take place on April 13-14, 2024, at the InterContinental Hotel in Hefei, Anhui, P.R.China. 

The topic is “Histiocytic/Dendritic Cell Proliferations, Neoplasms, and Mimics".  In addition to Sessions focused on given categories of the topic, there will be one Session designated specifically for Multidisciplinary Case Discussions. This Joint Workshop is a historic event, which symbolizes the scientific collaborations of the three societies.

Background

Histiocytic/Dendritic cells include many subgroups of different origins and functions. Most of these cells play a role in detecting and processing pathogens, recruiting other immune cells and initiating adaptive immunity by presenting antigens to T cells, establishing a link between the innate and adaptive immune responses. The term “histiocyte” has been variably defined, either being equated with “macrophage” or encompassing both macrophage and dendritic cell.

The neoplastic counterparts of histiocyte/dendritic cells manifest as many entities, including various histiocytoses, as well as Rosai-Dorfman disease (RDD) and ALK-positive histiocytosis, the latter two newly added to the 5th edition of the WHO Classification of Haematolymphoid Tumours. Mature plasmacytoid dendritic cell proliferations associated with myeloid neoplasms and blastic pDC neoplasm represent the neoplastic counterparts of the plasmacytoid dendritic cells.

Recent studies have provided new insights into understanding cellular origins and molecular mechanisms of histiocytic/dendritic cell disorders. For example, several histiocytic neoplasms including Langerhans cell histiocytosis/sarcoma, Erdheim-Chester disease, juvenile xanthogranuloma, RDD, and histiocytic sarcoma have demonstrated common mutations involving genes of MPAK pathway. 

In practice, due to the rarity and overlapping features of Histiocytic/Dendritic cell disorders, accurate diagnosis and assessment present unique challenges and pragmatic difficulties to pathologists. 

Objectives

The Workshop will focus on the following goals and overarching objectives:

1). Illustrate overlapping features and diagnostic challenges of histiocytic/dendritic cell proliferations, neoplasms, and mimics;

2). Identify molecular genetics that may distinguish histiocytic/dendritic cell reactive proliferations from their neoplastic counterparts;

3). Elucidate and expand the diagnostic criteria set by recent classification schemes with a view to informing future classifications; 

4). Develop consensus recommendations in approaches to distinguishing the histiocytic/dendritic cell proliferations and neoplasms with overlapping features.