Bone marrow examination is an important part of the workup of patients with lymphoma. It is often performed for staging purposes as well as for follow-up to evaluate for response to therapy or recurrence. In some patients, a diagnosis of…
Definition Lymphoproliferative disorders (LPDs) associated with iatrogenic immunodeficiency constitute a spectrum of lymphoid or plasmacytic proliferations, including a major subset that occurs after solid organ, stem cell, or bone marrow transplantation (post-transplant lymphoproliferative disorders [PTLDs]). A smaller number of cases…
Human primary immunodeficiencies (PIDs) are inborn errors of the immune system and comprise over 260 different genetic disorders. PIDs often result in predisposition to infection and tend to present early in life, with high morbidity and high mortality if left…
The Histiocytes This chapter reviews aspects of Langerhans cell histiocytosis as a prototypical representative of the condition, and this is followed by consideration of the histiocytic and dendritic cell sarcomas and disseminated juvenile xanthogranuloma. Advances in these conditions since the…
The histiocytoses are a group of disorders characterized by the proliferation of macrophages and dendritic cells. The contemporary classification of histiocytic disorders (a classification proposed by the Reclassification Working Group of the Histiocyte Society and the World Health Organization Committee…
Definition Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignant neoplasm characterized by the clonal proliferation of immature plasmacytoid dendritic cells (PDCs), also known as professional type I interferon-producing cells, or their precursors. Previously known under different names…
Eosinophilia is an increase in the number of circulating eosinophils accompanied by an increase of eosinophils and precursors in the bone marrow and often in other tissues as well. The upper limit of normal for the eosinophil count, if subjects…
The most common subtype of cutaneous mastocytosis, termed urticaria pigmentosa, was first described in the 19th century, a decade before mast cells (MCs) were defined by Paul Ehrlich as metachromatic cells of the connective tissue. In 1949, the first histologic…
The myelodysplastic/myeloproliferative neoplasms (MDS/MPNs) are clonal myeloid disorders that, at the time of initial diagnosis, have some clinical, laboratory, or morphologic features supporting the diagnosis of a myelodysplastic syndrome (MDS), such as persistent cytopenias and dysplasia involving one or more…
Definition The myeloproliferative neoplasms (MPNs) are clonal hematopoietic disorders characterized by proliferation of cells of one or more of the myeloid lineages, erythroid, granulocytic, or megakaryocytic. Initially, the proliferation in the bone marrow is effective and associated with maturation of…