Tumors of the hematopoietic and lymphoid tissues or tumours of the haematopoietic and lymphoid tissues are tumors that affect the blood, bone marrow, lymph, and lymphatic system. Because these tissues are all intimately connected through both the circulatory system and the immune system, a disease affecting one will often affect the others as well, making aplasia, myeloproliferation and lymphoproliferation closely related and often overlapping problems. While uncommon in solid tumors, chromosomal translocations are a common cause of these diseases. This commonly leads to a different approach in diagnosis and treatment of hematological malignancies. Hematological malignancies are malignant neoplasms ("cancer"), and they are generally treated by specialists in hematology and/or oncology. In some centers "hematology/oncology" is a single subspecialty of internal medicine while in others they are considered separate divisions. Not all hematological disorders are malignant ("cancerous"); these other blood conditions may also be managed by a hematologist.
Langerhans cell histiocytosis (LCH) is an abnormal clonal proliferation of Langerhans cells, abnormal cells deriving from bone marrow and capable of migrating from skin to lymph nodes.
A histiocyte is a vertebrate cell that is part of the mononuclear phagocyte system. The mononuclear phagocytic system is part of the organism's immune system. The histiocyte is a tissue macrophage or a dendritic cell. Part of their job is to clear out neutrophils once they've reached the end of their lifespan.
Malignant histiocytosis is a rare hereditary disease found in the Bernese Mountain Dog and humans, characterized by histiocytic infiltration of the lungs and lymph nodes. The liver, spleen, and central nervous system can also be affected. Histiocytes are a component of the immune system that proliferate abnormally in this disease. In addition to its importance in veterinary medicine, the condition is also important in human pathology.
Letterer–Siwe disease, (LSD) or Abt-Letterer-Siwe disease, is one of the four recognized clinical syndromes of Langerhans cell histiocytosis (LCH) and is the most severe form, involving multiple organ systems such as the skin, bone marrow, spleen, liver, and lung. Oral cavity and gastrointestinal involvement may also be seen. LCH and all its subtypes are characterized by monoclonal migration and proliferation of specific dendritic cells.
A histiocytoma in the dog is a benign tumor. It is an abnormal growth in the skin of histiocytes (histiocytosis), a cell that is part of the immune system. A similar disease in humans, Hashimoto-Pritzker disease, is also a Langerhans cell histiocytosis. Dog breeds that may be more at risk for this tumor include Bulldogs, American Pit Bull Terriers, American Staffordshire Terriers, Scottish Terriers, Greyhounds, Boxers, and Boston Terriers. They also rarely occur in goats and cattle.
Splenic marginal zone lymphoma (SMZL) is a type of cancer made up of B-cells that replace the normal architecture of the white pulp of the spleen. The neoplastic cells are both small lymphocytes and larger, transformed lymphoblasts, and they invade the mantle zone of splenic follicles and erode the marginal zone, ultimately invading the red pulp of the spleen. Frequently, the bone marrow and splenic hilar lymph nodes are involved along with the peripheral blood. The neoplastic cells circulating in the peripheral blood are termed villous lymphocytes due to their characteristic appearance.
Diffuse large B-cell lymphoma (DLBCL) is a cancer of B cells, a type of lymphocyte that is responsible for producing antibodies. It is the most common form of non-Hodgkin lymphoma among adults, with an annual incidence of 7–8 cases per 100,000 people per year in the US and UK. This cancer occurs primarily in older individuals, with a median age of diagnosis at ~70 years, although it can occur in young adults and, in rare cases, children. DLBCL can arise in virtually any part of the body and, depending on various factors, is often a very aggressive malignancy. The first sign of this illness is typically the observation of a rapidly growing mass or tissue infiltration that is sometimes associated with systemic B symptoms, e.g. fever, weight loss, and night sweats.
Erdheim–Chester disease (ECD) is an extremely rare disease characterized by the abnormal multiplication of a specific type of white blood cells called histiocytes, or tissue macrophages. It was declared a histiocytic neoplasm by the World Health Organization in 2016. Onset typically is in middle age, although younger patients have been documented. The disease involves an infiltration of lipid-laden macrophages, multinucleated giant cells, an inflammatory infiltrate of lymphocytes and histiocytes in the bone marrow, and a generalized sclerosis of the long bones.
In hematology, hemophagocytic lymphohistiocytosis (HLH), also known as haemophagocytic lymphohistiocytosis, and hemophagocytic or haemophagocytic syndrome, is an uncommon hematologic disorder seen more often in children than in adults. It is a life-threatening disease of severe hyperinflammation caused by uncontrolled proliferation of benign lymphocytes and macrophages that secrete high amounts of inflammatory cytokines. It is classified as one of the cytokine storm syndromes. There are inherited and non-inherited (acquired) causes of HLH.
Chronic multifocal Langerhans cell histiocytosis, previously known as Hand–Schüller–Christian disease, is a type of Langerhans cell histiocytosis (LCH), which can affect multiple organs. The condition is traditionally associated with a combination of three features; bulging eyes, breakdown of bone, and diabetes insipidus, although around 75% of cases do not have all three features. Other features may include a fever and weight loss, and depending on the organs involved there may be rashes, asymmetry of the face, ear infections, signs in the mouth and the appearance of advanced gum disease. Features relating to lung and liver disease may occur.
Lymphoid hyperplasia is the rapid proliferation of normal lymphocytic cells that resemble lymph tissue which may occur with bacterial or viral infections. The growth is termed hyperplasia which may result in enlargement of various tissue including an organ, or cause a cutaneous lesion.
Rosai–Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy or sometimes as Destombes–Rosai–Dorfman disease, is a rare disorder of unknown cause that is characterized by abundant histiocytes in the lymph nodes or other locations throughout the body.
Non-Langerhans cell histiocytosis refers to a family of histiocytosis characterized by the absence of Langerhans cells.
Histiocytic diseases in dogs are a group of diseases in dogs which may involve the skin, and which can be difficult to differentiate from granulomatous, reactive inflammatory or lymphoproliferative diseases. The clinical presentation and behaviour as well as response to therapy vary greatly among the syndromes.
The Xanthogranulomatous Process (XP), is a form of acute and chronic inflammation characterized by an exuberant clustering of foamy macrophages among other inflammatory cells. Localization in the kidney and renal pelvis has been the most frequent and better known occurrence followed by that in the gallbladder but many others have been subsequently recorded. The pathological findings of the process and etiopathogenetic and clinical observations have been reviewed by Cozzutto and Carbone.
Epstein–Barr virus–associated lymphoproliferative diseases are a group of disorders in which one or more types of lymphoid cells, i.e. B cells, T cells, NK cells, and histiocytic-dendritic cells, are infected with the Epstein–Barr virus (EBV). This causes the infected cells to divide excessively, and is associated with the development of various non-cancerous, pre-cancerous, and cancerous lymphoproliferative disorders (LPDs). These LPDs include the well-known disorder occurring during the initial infection with the EBV, infectious mononucleosis, and the large number of subsequent disorders that may occur thereafter. The virus is usually involved in the development and/or progression of these LPDs although in some cases it may be an "innocent" bystander, i.e. present in, but not contributing to, the disease.
T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL) is a malignancy of B cells. B-cells are lymphocytes that normally function in the humoral immunity component of the adaptive immune system by secreting antibodies that, for example, bind to and neutralize invasive pathogens. Among the various forms of B-cell lymphomas, THRLBCL is a rarely occurring subtype of the diffuse large B-cell lymphomas (DLBCL). DLBCL are a large group of lymphomas that account for ~25% of all non-Hodgkin lymphomas worldwide. THRLBCL is distinguished from the other DLBCL subtypes by the predominance of non-malignant T-cell lymphocytes and histiocytes over malignant B-cells in its tumors and tissue infiltrates.
The Histiocyte Society is an international network of people that co-ordinate studies of the histiocytoses, which it has divided into Langerhans cell histiocytosis, non-Langerhans cell histiocytoses, and malignant histiocytosis. They provided the criteria to definitively diagnose Langerhans cell histiocytosis.
Crystal-storing histiocytosis is a form of histiocytosis which mostly occurs in people with monoclonal gammopathies. Histiocytosis is an excessive number of histiocytes. In the vast majority of crystal-storing histiocytosis cases, immunoglobulins accumulate within the cytoplasm of histiocytes; in rare cases clofazimine, cystine, silica, or Charcot–Leyden crystals may be found in the histiocytes instead. Non-immunoglobulin crystal-storing histiocytosis is mostly associated with non-malignant disorders, such as chronic inflammation or autoimmune abnormality conditions such as rheumatoid arthritis, Crohn's disease, or Helicobacter pylori gastritis. It may be a localised or generalised disease. Examples of locations where histiocytosis may occur include the lungs, pleura, stomach, kidney, bone marrow, thyroid, thymus, and parotid gland. The disease is described as generalised if two or more unrelated sites are involved.
