Interdigitating dendritic cell sarcoma and follicular dendritic cell sarcoma: histopathological findings for differential diagnosis.

Both interdigitating cell sarcoma (IDCS) and follicular dendritic cell sarcoma (FDCS) are rare neoplasms derived from dendritic cells in lymphoid organs. IDCS is defined as a neoplastic proliferation of spindle-shaped to ovoid cells with phenotypic features similar to those of IDCs. FDCS is a malignant neoplasm derived from FDCs that possess and present antigens to B cells in the follicular (germinal) centers of lymphoid organs. They often occur in lymph nodes, although they can also arise at extranodal sites. In this review, we have highlighted the morphological and immunohistochemical properties of these neoplasms, which could help in unequivocal and accurate diagnosis.