T-cell/histiocyte-rich large B-cell lymphoma | |
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Other names | THRLBCL |
Specialty | Hematology, Oncology, |
Differential diagnosis | Variant form of nodular lymphocyte predominant Hodgkin lymphoma |
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. [1] 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. [2]
THRLBCL commonly afflicts middle-aged individuals but has been diagnosed in rare pediatric cases. [1] The disease usually presents with lymphadenopathy, i.e. bulky enlargements of lymph nodes in the neck, arm pit, or groin. However, most cases are at an advanced stage at diagnoses: further examinations frequently reveal that the disease has spread to multiple internal organs and tissues. The course of the disease is usually characterized as being poorly responsive to treatment: the disease's survival rates in past studies have been only ~46%. [3] However, recent studies suggest that novel treatments can improve these survival rates.
Many studies have found that THRLBCL can overlap with the variant form of nodular lymphocyte predominant Hodgkin lymphoma (NLPHL). That is, some cases of variant NLPHL, which is a relatively indolent malignancy, share with THRLBCL similar disease presentations, histologies (i.e. microscopic appearances), genetic abnormalities, and apparent etiologies. [4] Indeed, NLPHL can, in rare cases, progress into THRLBCL. [2] Comapared to THRLBCL, however, these variant NLPHL cases are less aggressive, are more responsive to treatment, and have a better prognosis. [4] Thus, THRLBCL and NLPHL may be biologically related diseases that represent opposite ends of a severity spectrum. [5]
T-cell/histiocyte-rich large B-cell lymphoma most commonly afflicts middle-aged (i.e. 49–57 years old) individuals but has been diagnosed in persons aged 4 [6] to 92 years. [2] The disease has a male predominance ranging between 1.7:1 [3] to 3:1 [2] in different studies. In a review of 36 reported pediatric cases, the male to female ratio was 4:1. [6] Patients typically present with enlarged lymph nodes in the neck, arm pit, and groin areas but on further examination are found to have involvement of their spleen (31% of cases), liver (52% of cases), bone marrow (27% of cases) [7] and lung/or (13%) as determined by finding enlarged spleens and/or livers on physical examination or medical imaging; abnormal results on liver function tests, and/or THRLBCL infiltrates in bone marrow biopsies. [3] Rare cases of the disease have presented with involvement of the skin (termed primary cutaneous THRLBCL), thyroid gland, thymus, gastrointestinal tract, pancreas, [8] jaw bone, [7] nasopharynx, brain, tongue, uterus, stomach, and soft tissues. [9] Many patients will also complain of having systemic B symptoms such as fever, night sweats, weight loss, and malaise. [2]
Due to its rarity, the causes of THRLBCL have not been well studied and consequently remained unclear. The malignant B-cells in the disease commonly have mutations in several genes such as: [2]
The neoplastic cells in this disease also show gains on the short arm of chromosome 2 at position 16.1 which affect the REL protooncogene [3] which codes for c-Rel, a protein that controls the maturation of B-cells and is implicated in the development of many cancers including lymphomas; [15] as well as losses o the short armes of chromosomes 1 and 9 and 19.2 and 11.2 sites, respectively. [3] These studies allow the possibility that THRLBC, similar to the other subtypes of DLBDL as well as a wide array of other cancers [16] results at least in part from the step-wise development of gene changes such as mutations, altered expressions, amplifications (i.e. increases in the number of copies of specific genes), and chromosomal translocations that alter the expression of key genes in B-cells to result in the increasingly malignant behavior of these cells. [17] However, the underlying causes for these gene changes as well as the identity of the genes whose changes contribute to the malignant behavior of the neoplastic B-cells in THRLBC have yet to be defined. [3]
The neoplastic B-cells in THRLBCL infiltrations are dominated by high numbers of histiocytes and dendritic cells. Studies suggest that the latter cells help to create a microenvironment that is tolerant or promotes tumor growth and spread to other sites. [4]
The diagnosis of THRLBCL, particularly as it pertains to differentiating it from DLBCL and other lymphomas, depends on examining involved tissues obtained by biopsy or operation for their histology, i.e. microscopic anatomy. The tissues involved in THRLBCL commonly show an effacement of their normal architecture by a diffusely growing infiltrate of non-malignant T-cell lymphocytes, histiocytes, and neoplastic (i.e. malignant) B-cells. The malignant B-cells represent <10% of the cells in these lesions [3] and bear resemblances to centroblast, immunoblasts, and/or the Reed–Sternberg cells found in Hodgkin disease, including in particular Hodgkin disease's nodular variant. [2] The non-malignant T-cells generally have a reactive morphology as indicated by their larger than normal size and irregularly shaped cell nuclei. [3] And, the histiocytes, which are not always present in these lesions, have a non-epithelial cell appearance. [3] These infiltrates often resemble these seen in inflammation. [8] The malignant B-cells in THRLBCL are definitively identified by immunophenotyping to detect B-cell marker proteins (e.g. CD19, CD20, CD22, CD79a, and/or PAX5). [4] These cells may also express other identifying marker proteins such as Bcl-6 (50–90% of cases), the product of the MYC gene, c-Myc (most cases), Bcl-2 (40% of cases), MUC1 (30% of cases), and, in a minority of cases, CD10. [2] The T cells in these lesions are predominantly cytotoxic T cells as indicated by their expression of T-cell receptor, CD8 T-cell co-receptor, and CD5 cell surface proteins. And, the histiocytes in these lesions express CD68 and CD163 cell surface proteins. Before making a diagnosis of THRLBCL in a pediatric population, congenital and acquired immunodeficiency diseases, which can cause aberrant immune responses with a histology similar to THRLBCL, must be ruled-out. [3]
While the histological features of THRLBCL are distinctly different that those found in other DLBCL subtypes, they can closely resemble, and be mistaken for, those found in the variant form of nodular lymphocyte predominant Hodgkin lymphoma. [4] Some important histological features that favor the diagnosis of THRLBCL over NLPHL include the presence of:
Patients diagnosed with THRLBCL have been treated with chemotherapy regimens similar to the regimens used to treat DLBCL. These earlier used chemotherapy regimens (e.g. the CHOP regimen consisting of three chemotherapy drugs (cyclophosphamide, hydroxydoxorubicin, and oncovin) plus a glucocorticoid, either prednisone or prednisolone) [7] achieve complete response rates of 48% to 85%, 3-year overall survival rates of 50% to 64%, and 5-year overall survival rates of 46% to 58%. The addition of immunotherapy drug, rituximab, to the CHOP regimen appears to have improved these results: in one study, patients receiving the R-CHOP regimen had a three-year overall survival rate of 75%. [8] Since treatment of the variant form of nodular lymphocyte predominant Hodgkin lymphoma using different and less aggressive drug regimens achieves better results than the regimens used to treat THRLBCL, it is clinically important to distinguish the two diseases. [4]
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.
Anaplastic large-cell lymphoma (ALCL) refers to a group of non-Hodgkin lymphomas in which aberrant T cells proliferate uncontrollably. Considered as a single entity, ALCL is the most common type of peripheral lymphoma and represents ~10% of all peripheral lymphomas in children. The incidence of ALCL is estimated to be 0.25 cases per 100,000 people in the United States of America. There are four distinct types of anaplastic large-cell lymphomas that on microscopic examination share certain key histopathological features and tumor marker proteins. However, the four types have very different clinical presentations, gene abnormalities, prognoses, and/or treatments.
Follicular lymphoma (FL) is a cancer that involves certain types of white blood cells known as lymphocytes. The cancer originates from the uncontrolled division of specific types of B-cells known as centrocytes and centroblasts. These cells normally occupy the follicles (nodular swirls of various types of lymphocytes) in the germinal centers of lymphoid tissues such as lymph nodes. The cancerous cells in FL typically form follicular or follicle-like structures (see adjacent Figure) in the tissues they invade. These structures are usually the dominant histological feature of this cancer.
Primary effusion lymphoma (PEL) is classified as a diffuse large B cell lymphoma. It is a rare malignancy of plasmablastic cells that occurs in individuals that are infected with the Kaposi's sarcoma-associated herpesvirus. Plasmablasts are immature plasma cells, i.e. lymphocytes of the B-cell type that have differentiated into plasmablasts but because of their malignant nature do not differentiate into mature plasma cells but rather proliferate excessively and thereby cause life-threatening disease. In PEL, the proliferating plasmablastoid cells commonly accumulate within body cavities to produce effusions, primarily in the pleural, pericardial, or peritoneal cavities, without forming a contiguous tumor mass. In rare cases of these cavitary forms of PEL, the effusions develop in joints, the epidural space surrounding the brain and spinal cord, and underneath the capsule which forms around breast implants. Less frequently, individuals present with extracavitary primary effusion lymphomas, i.e., solid tumor masses not accompanied by effusions. The extracavitary tumors may develop in lymph nodes, bone, bone marrow, the gastrointestinal tract, skin, spleen, liver, lungs, central nervous system, testes, paranasal sinuses, muscle, and, rarely, inside the vasculature and sinuses of lymph nodes. As their disease progresses, however, individuals with the classical effusion-form of PEL may develop extracavitary tumors and individuals with extracavitary PEL may develop cavitary effusions.
Nodular fasciitis (NF) is a benign, soft tissue tumor composed of myofibroblasts that typically occurs in subcutaneous tissue, fascia, and/or muscles. The literature sometimes titles rare NF variants according to their tissue locations. The most frequently used and important of these are cranial fasciitis and intravascular fasciitis. In 2020, the World Health Organization classified nodular fasciitis as in the category of benign fibroblastic/myofibroblastic tumors. NF is the most common of the benign fibroblastic proliferative tumors of soft tissue.
The B-cell lymphomas are types of lymphoma affecting B cells. Lymphomas are "blood cancers" in the lymph nodes. They develop more frequently in older adults and in immunocompromised individuals.
Intravascular lymphomas (IVL) are rare cancers in which malignant lymphocytes proliferate and accumulate within blood vessels. Almost all other types of lymphoma involve the proliferation and accumulation of malignant lymphocytes in lymph nodes, other parts of the lymphatic system, and various non-lymphatic organs but not in blood vessels.
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.
Richter's transformation (RT), also known as Richter's syndrome, is the conversion of chronic lymphocytic leukemia (CLL) or its variant, small lymphocytic lymphoma (SLL), into a new and more aggressively malignant disease. CLL is the circulation of malignant B lymphocytes with or without the infiltration of these cells into lymphatic or other tissues while SLL is the infiltration of these malignant B lymphocytes into lymphatic and/or other tissues with little or no circulation of these cells in the blood. CLL along with its SLL variant are grouped together in the term CLL/SLL.
Marginal zone B-cell lymphomas, also known as marginal zone lymphomas (MZLs), are a heterogeneous group of lymphomas that derive from the malignant transformation of marginal zone B-cells. Marginal zone B cells are innate lymphoid cells that normally function by rapidly mounting IgM antibody immune responses to antigens such as those presented by infectious agents and damaged tissues. They are lymphocytes of the B-cell line that originate and mature in secondary lymphoid follicles and then move to the marginal zones of mucosa-associated lymphoid tissue, the spleen, or lymph nodes. Mucosa-associated lymphoid tissue is a diffuse system of small concentrations of lymphoid tissue found in various submucosal membrane sites of the body such as the gastrointestinal tract, mouth, nasal cavity, pharynx, thyroid gland, breast, lung, salivary glands, eye, skin and the human spleen.
Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is a slow-growing CD20 positive form of Hodgkin lymphoma, a cancer of the immune system's B cells.
Extranodal NK/T-cell lymphoma, nasal type (ENKTCL-NT) is a rare type of lymphoma that commonly involves midline areas of the nasal cavity, oral cavity, and/or pharynx At these sites, the disease often takes the form of massive, necrotic, and extremely disfiguring lesions. However, ENKTCL-NT can also involve the eye, larynx, lung, gastrointestinal tract, skin, and various other tissues. ENKTCL-NT mainly affects adults; it is relatively common in Asia and to lesser extents Mexico, Central America, and South America but is rare in Europe and North America. In Korea, ENKTCL-NT often involves the skin and is reported to be the most common form of cutaneous lymphoma after mycosis fungoides.
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.
Monomorphic epitheliotropic intestinal T cell lymphoma (MEITL) is an extremely rare peripheral T-cell lymphoma that involves the malignant proliferation of a type of lymphocyte, the T cell, in the gastrointestinal tract. Over time, these T cells commonly spread throughout the mucosal lining of a portion of the GI tract, lead to GI tract nodules and ulcerations, and cause symptoms such as abdominal pain, weight loss, diarrhea, obstruction, bleeding, and/or perforation.
Pediatric-type follicular lymphoma (PTFL) is a disease in which malignant B-cells accumulate in, overcrowd, and cause the expansion of the lymphoid follicles in, and thereby enlargement of the lymph nodes in the head and neck regions and, less commonly, groin and armpit regions. The disease accounts for 1.5% to 2% of all the lymphomas that occur in the pediatric age group.
Primary testicular diffuse large B-cell lymphoma (PT-DLBCL), also termed testicular diffuse large B-cell lymphoma and diffuse large B-cell lymphoma of the testes, is a variant of the diffuse large B-cell lymphomas (DLBCL). DLBCL are a large and diverse group of B-cell malignancies with the great majority (-85%) being typed as diffuse large B-cell lymphoma, not otherwise specified. PT-DLBCL is a variant of DLBCL, NOS that involves one or, in uncommon cases, both testicles. Other variants and subtypes of DLBCL may involve the testes by spreading to them from their primary sites of origin in other tissues. PT-DLBCL differs from these other DLBCL in that it begins in the testes and then may spread to other sites.
Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT) is a cutaneous lymphoma skin disease that occurs mostly in elderly females. In this disease, B cells become malignant, accumulate in the dermis and subcutaneous tissue below the dermis to form red and violaceous skin nodules and tumors. These lesions typically occur on the lower extremities but in uncommon cases may develop on the skin at virtually any other site. In ~10% of cases, the disease presents with one or more skin lesions none of which are on the lower extremities; the disease in these cases is sometimes regarded as a variant of PCDLBL, LT termed primary cutaneous diffuse large B-cell lymphoma, other (PCDLBC-O). PCDLBCL, LT is a subtype of the diffuse large B-cell lymphomas (DLBCL) and has been thought of as a cutaneous counterpart to them. Like most variants and subtypes of the DLBCL, PCDLBCL, LT is an aggressive malignancy. It has a 5-year overall survival rate of 40–55%, although the PCDLBCL-O variant has a better prognosis than cases in which the legs are involved.
Diffuse large B-cell lymphoma associated with chronic inflammation (DLBCL-CI) is a subtype of the Diffuse large B-cell lymphomas and a rare form of the Epstein–Barr virus-associated lymphoproliferative diseases, i.e. conditions in which lymphocytes infected with the Epstein-Barr virus (EBV) proliferate excessively in one or more tissues. EBV infects ~95% of the world's population to cause no symptoms, minor non-specific symptoms, or infectious mononucleosis. The virus then enters a latency phase in which the infected individual becomes a lifetime asymptomatic carrier of the virus. Some weeks, months, years, or decades thereafter, a very small fraction of these carriers, particularly those with an immunodeficiency, develop any one of various EBV-associated benign or malignant diseases.
Fibrin-associated diffuse large B-cell lymphoma (FA-DLBCL) is an extremely rare form of the diffuse large B-cell lymphomas (DLBCL). DLBCL are lymphomas in which a particular type of lymphocyte, the B-cell, proliferates excessively, invades multiple tissues, and often causes life-threatening tissue damage. DLBCL have various forms as exemplified by one of its subtypes, diffuse large B-cell lymphoma associated with chronic inflammation (DLBCL-CI). DLBCL-CI is an aggressive malignancy that develops in sites of chronic inflammation that are walled off from the immune system. In this protected environment, the B-cells proliferate excessively, acquire malignant gene changes, form tumor masses, and often spread outside of the protected environment. In 2016, the World Health Organization provisionally classified FA-DLBCL as a DLBCL-CI. Similar to DLBCL-CI, FA-DLBCL involves the proliferation of EBV-infected large B-cells in restricted anatomical spaces that afford protection from an individual's immune system. However, FA-DLBCL differs from DLBCL-CI in many other ways, including, most importantly, its comparatively benign nature. Some researchers have suggested that this disease should be regarded as a non-malignant or pre-malignant lymphoproliferative disorder rather than a malignant DLBCL-CI.