ABSTRACT
The World Health Organization (WHO) classification of histiocytic and dendritic cell neoplasms is summarized in Box 9.1 (Swerdlow et al. 2008).
These are uncommon neoplasms, often represented in the literature as small series or single-case reports. They include neoplasms of macrophages and interdigitating dendritic cells (IDCs), both derived from haemopoietic precursors; and neoplasms of follicular dendritic cells, which are of mesenchymal origin and arise from ubiquitous perivascular precursor cells (Krautler et al. 2012). Neoplasms of IDCs and follicular dendritic cells have in the past been designated as ‘sarcoma/tumour’ to encompass the variable
cytological grade and behaviour of these tumours: not all are clearly sarcomatous, but the majority are prone to multiple recurrences and metastasis.
