Histiocytic and Dendritic Cell Neoplasms

Histiocytic and dendritic cell neoplasms are derived from cells with phenotypic features of native mature histiocytes/macrophages and dendritic cells. They are extremely rare and heterogeneous group of neoplasm but share some clinical features of having distinct isolated or disseminated forms. They can present as nodal, extranodal and/or both, and occur across all age groups, with a tendency to present with more disseminated and aggressive forms in the early childhood period. Diagnosis is essentially based on immunohistomorphological features; however, in view of physiological functional overlap, this broad group of tumor is endowed with certain degree of histological overlap across different entities. Thus, it is prudent to take a note of relevant clinical (including radiological) features for making an appropriate diagnosis. Recent inputs from high-throughput molecular technologies about the certain driver mutations have also contributed to a certain extent in further deciphering the pathogenesis of some of these uncommon enigmatic tumors.