Dendritic Cell Neoplasms Histiocytes have two broad functions: antigen processing and antigen presentation. In Chapter 77, the focus was on neoplasms derived from antigen-processing cells; that is, phagocytic histiocytes/macrophages. In…
Introduction Benign and malignant neoplasms of nonlymphoid cell components of lymph nodes are remarkably rare. They may have a vascular origin (see Part IX) or arise from a variety of…
Lymphoproliferative Disorders Associated with Congenital Immune Deficiencies Definition A lymphoproliferative disease arising in the setting of a primary immune deficiency (PID) or a primary immunoregulatory disorder (1). Epidemiology Congenital immunodeficiency…
Post-Transplant Lymphoproliferative Disorders Definition Post-transplant lymphoproliferative disorders (PTLDs) are lymphoid proliferations that arise in patients who have undergone solid organ or bone marrow transplantation (1). PTLDs are heterogeneous, encompassing a…
Anaplastic Large-Cell Lymphoma Anaplastic large-cell lymphoma (ALCL) was originally designated as Ki-1 lymphoma by Stein and colleagues in 1985 (1). The name was based on the constant and uniform positivity…
Introduction The immune system, composed of a multitude of interdependent humoral and cellular components, as well as non-specific host defense mechanisms (e.g., phagocytes), defends the body against environmental pathogens. Deficiencies…
Histiocytic Sarcoma Definition As defined in the World Health Organization (WHO) classification, histiocytic sarcoma is a malignant neoplasm composed of cells with histologic and immunophenotypic features similar to those of…
Myeloid Sarcoma Definition A tumor mass of immature myeloid cells involving an extramedullary site or bone (1). The neoplasm can precede, occur concurrently, or arise subsequent to the diagnosis of…
Angioimmunoblastic T-Cell Lymphoma Definition Angioimmunoblastic T-cell lymphoma (AILT) is a specific type of peripheral T-cell lymphoma that is characterized by lymphadenopathy, systemic disease, and associated immunodysregulation and immunodeficiency (1). Synonyms…
Introduction In addition to its various populations of lymphocytes, lymph nodes are composed of other cell types, including cells derived from the monocytic lineage, and cells that comprise the lymph…
