Updates in histiocytic and dendritic cell proliferations and neoplasms

Tumours derived from histiocytes/macrophages and from dendritic cells are extremely rare. They mainly occur in lymphoid tissues, where they account for less than 1% of tumours, but they can be also found in extranodal sites. These neoplasms represent a heterogeneous group of diseases with a variable clinical behavior even within the same tumour entity, ranging from localized and indolent forms to systemic aggressive processes. Diagnosis is based on histological and immunophenotypic features, but overlaps occur across diseases with different biological nature and clinical course, thus correlation with clinical and radiological features is sometimes necessary for final diagnosis. The driver mutations identified during the last few years contributed to a better understanding of the pathogenesis of some of these tumours and in some of them turned out to be useful for diagnosis and treatment