Intravascular lymphomas | |
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Other names | Subtypes: intravascular large B-cell lymphoma; intravascular NK/T-cell lymphoma; intravascular NK-cell lymphoma; Intravasular T-cell lymphoma |
Micrograph showing an intravascular large B-cell lymphoma in a blood vessel of the brain. H&E stain. | |
Specialty | Hematology, oncology, dermatology |
Causes | Epstein–Barr virus for intravascular NK- and T-cell lymphomas |
Prognosis | Guarded |
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 (e.g. the spleen), and various non-lymphatic organs (e.g. bone marrow and liver) but not in blood vessels. [1]
IVL fall into three different forms based on the type of lymphocyte causing the disease. Intravascular large B-cell lymphoma (IVBCL), which constitutes ~90% of all IVL, is a lymphoma of malignant B-cell lymphocytes [2] as classified by the World Health Organization, 2016. [3] The remaining IVL types, which have not yet been formally classified by the World Health Organization, are defined based mainly on case reports; [1] these IVL are 1) intravascular NK-cell lymphoma (IVNKL) in which the malignant cells are a type of T cell lymphocyte termed natural killer cells (NK-cells) and 2) intravascular T-cell lymphoma (IVTL) in which the neoplastic cells are primarily, if not exclusively, a type of t-cell termed cytotoxic T-cells. Because of their similarities and extreme rarities, IVL lymphomas caused by NK-cells and cytotoxic T-cells are often grouped together under the term intravascular NK/T cell lymphomas (IVNK/TL). [4] The malignant cells in IVNK/TL are typically infected with the Epstein–Barr virus suggesting that these lymphomas are examples of the Epstein-Barr virus-associated lymphoproliferative diseases. [4] Since infection with this virus is rarely seen in IVBCL, this form of IVL is not typically regarded as one of the Epstein-Barr virus-associated lymphoproliferative diseases. [2]
Intravascular large B-cell [5] and intravascular NK/T cell [4] IVL are typically very aggressive lymphomas that afflict middle-aged and elderly adults. At the time of diagnosis, they accumulate within small-sized and medium-sized but not large-sized blood vessels of the skin, central nervous system, and, less frequently. virtually any other organ system. Unlike most lymphomas, however, they generally do not accumulate or infiltrate lymph nodes. All of the IVL are frequently associated with systemic B symptoms such as fever and weight loss, as well as symptoms related to the other organs in which they accumulate in blood vessels, constrict blood flow, and thereby cause severe damage due to infarction, i.e. damage due to the loss of blood flow. [4] [5]
Historically, most cases of the intravascular lymphomas responded very poorly to standard chemotherapy regimens that were used to treat other types of the B-cell lymphomas. With few exceptions, these intravascular lymphomas progressed very rapidly. More recently, however, the addition to these chemotherapy regimens of the immunotherapy agents, Rituximab, which acts to kill B-cells, has greatly improved their effectiveness and thereby the prognosis of the most common form of these diseases, the intravascular B-cell lymphomas. [5] Unfortunately, no such agent that is directed against NK-cells or cytotoxic T-cells has yet been reported to be useful in treating these two types of the intravascular B-cell lymphomas.
In 1959, Pfleger and Tappeiner first reported on a cancer in which malignant cells grew uncontrollably within the lumen of blood vessels; the authors suggested that these malignant cells were derived from the endothelial cells lining the vasculature and therefore termed the disorder angioendotheliomatosis proliferans systemisata. [6] Subsequent studies reported in 1982, 1985, and 1986 led to the conclusion that these malignant cells were derived from lymphocytes rather than endothelial cells. These along with other studies termed the disease angioendotheliomatosis, neoplastic angiotheliomatosis, intravascular lymphomatosis, angioendotheliotropic (intravascular) lymphoma, angiotropic large-cell lymphoma, diffuse large-cell lymphoma, [7] intralymphatic lymphomatosis, and, less specifically, malignant angioendotheliomatosis or intravascular lymphoma. By 2001, the World Health Organization had defined the disease as a malignant B-cell lymphoma termed intravascular large B-cell lymphoma.[ citation needed ]
Santucci et al. first reported a case of IVL that involved malignant NK cells. Some 2 dozen other cases of intravascular NK cell lymphoma have been reported by 2018. [8] In 2008, 29 case reports of purported intravascular T-cell lymphoma were reviewed; only two of these cases were associated with evidence strongly suggesting that the malignant cells were cytotoxic T-cells. Subsequently, a few more cases of cytotoxic T-cell-based have been reported. There remains a possibility that future studies will find other T-cell types may cause IVTCL. [9]
Intravascular large B-cell lymphomas fall into three distinct variants, all of which involve the intravascular accumulation of malignant B-cells and appear to have a similar pathophysiology. However, they differ in the distribution of their lesions, types of populations affected, prognoses, and treatments. These three variants are: 1) intravascular large B-cell lymphoma classical, 2) intravascular large B-cell lymphoma, cutaneous variant, and 3) intravascular large B-cell lymphoma, hemophagocytic syndrome-associated variant. [5] The following sections give the common pathophysiology of the three variants and then describes the lesions, populations affected, prognoses, and treatments of each variant in separate sections.[ citation needed ]
The gene, chromosome, and gene expression abnormalities in IVBCL have not been fully evaluated. Studies to date indicate that the malignant cells in this disease have mutations in their MYD88 (44% of cases) and CD79B (26% of cases) genes. [5] The exact mutation seen in the MYD88 (i.e. L265P) [10] and some or the mutations in CD79B [11] occur in diverse types of lymphoma. Other abnormalities seen in the small numbers of cases that have been studied so far include translocations between chromosome 14 and 18; tandem triplications of both the BCL2 gene located on the long arm of chromosome 18 at position q21 and the KMT2A gene located on the long arm of chromosome 11 between positions 22 and 25. [5] The product protein of BCL2 viz., Bcl-2, regulates cell survival and apoptosis (i.e. programmed cell death) and the product protein of KMT2a viz., MLL regulates cell maturation. Abnormalities in BCL2 [12] and KMT2A [13] are associated with other types of B-cell lymphomas. It seems likely that these or other gene, chromosome, and/or gene expression abnormalities contribute to the development and/or progression of IVBCL.[ citation needed ]
The malignant B-cells in IVBCL fail to express the CD29 protein while the endothelial cells in close proximity to the intravascular accumulations of the malignant B-cells fail to express key CXC chemokine receptor proteins particularly CxcL12 but also Cxcr5, Ccr6, and/or Ccr7. The failure of the endothelial cells to express these receptor proteins may be due to the action of nearby malignant B-cells. In any event, all of the cited proteins are involved in the movement of B-cells from the intravascular space across the vascular endothelium and into tissues. The lack of these proteins may explain the accumulation of the malignant B-cells of IVLBC within blood vessels. [5]
In about 80% of cases, the malignant B-cells in IVBCL are "non-germinal center B-cells" as defined by the Hans algorithm [14] rather than the "germinal center B-cells" that are commonly found in less aggressive B-cell lymphomas. This factor may contribute to the aggressiveness of IVBCL. [5]
Individuals presenting with the classical variant of IVLBL are typically middle-aged or elderly (39–90 years) that have one or more of the following: systemic symptoms, particularly fever (45% of cases); [5] cutaneous lesions (40%); central nervous system disorders (35%); [2] and clinical and laboratory abnormalities involving the bone marrow (~18%), lung (~6%), and, rarely, endocrine glands (e.g. pituitary, thyroid, adrenal gland [2] ), liver, prostate, uterus, eye, intestine, and in individual cases almost any other organ or tissue. [15] These findings are based primarily on studies of 740 patients conducted in Europe; a study conducted in Quebec, Canada on 29 patients gave similar results. [15] Individuals may present with one, two, or more of these abnormalities. Systemic symptoms include not only the most commonly seen one viz., fever, but also malaise, weight loss, and other B symptoms; the cutaneous lesions include singular or multiple plaques, nodules, tumors, and ulcerations, some of which may be painful and most of which are located on the breast, lower abdomen, and/or extremities. Central nervous system defects include sensory and/or motor neuropathy, spinal nerve root pain, paresthesia, hypoesthesia, aphasia, dysarthria, hemiparesis, seizures, myoclonus, transient visual loss, vertigo, altered conscious states, and, particularly in relapsed disease, neurolymphomatosis (i.e. direct invasion of one or more nerves in the peripheral nervous system by the malignant B-cells). [5] Laboratory studies generally show non-specific abnormalities: elevated levels of serum lactate dehydrogenase and soluble IL2RA; [16] anemia, decreases in blood platelet levels, and decreases in white blood cell levels in 25%->50% of cases. [7] Circulating malignant B-cells are not found in 90-95% of cases [5] and laboratory evidence of organ injury is found in those cases involving these organs. [7]
The diagnosis of IVBCL is heavily dependent upon obtaining biopsy specimens from involved tissues, particularly the skin but in cases without skin lesions, other apparently involved tissues. Microscopic examination of these tissues typically shows medium-sized to large-sized lymphocytes located within small- to medium-sized blood vessels of the skin, lung, and other tissues or the sinusoids of the liver, bone marrow, and spleen. On occasion, these malignant cells have the appearance of Reed-Sternberg cells. The lesions should show no or very little extension outside of blood vessels. As determined by immunohistochemistry analyses, the intravascular malignant lymphocytes express typical B-cell proteins, particularly CD20, which is found in almost all cases, CD79a and Pax5, which are found in most cases, [5] and MUM1 and Bcl-2, which are found in 95% and 91% of cases, respectively. [2] These B-cells are usually (80% of cases) non-germinal center B-cells (see Pathophysiology section) and may express one or more of the gene, chromosome, and gene expression abnormalities described in the above Pathophysiology section. Since the classical variant can present with a wide range of clinical signs, symptoms, and organ involvements, its presence may not be apparent, particularly in cases that do not exhibit clinically apparent skin lesions. Accordingly, random skin biopsies have been used to obtain evidence of IVL in cases that have signs and/or symptoms of the disease that are restricted to non-cutaneous sites, [2] even in cases that present with no other finding except unexplained fever. [17] The diagnosis of IVBCL, classical variant is solidified by finding these pathological features in more than one site. [2]
At diagnosis, IVBCL must be regarded as an aggressive and disseminated malignancy requiring systemic chemotherapy. In the absence of long- or short-term, controlled clinical trials on treating this lymphoma, individuals with IVBCL have been treated with the standard regimen used to treat diffuse large B-cell lymphomas viz., the CHOP chemotherapy regimen which consists of cyclophosphamide, hydroxydaunorubicin (also termed doxorubicin or adriamycin), oncovin (also termed vincristine), and a corticosteroid (i.e. either prednisone or prednisolone) plus the monoclonal antibody immunotherapy agent, Rituximab. This immunochemotherapeutic regimen has achieved an overall survival rate at 3 years of 81%; this overall survival rate using CHOP before Retuximab was added to the regimen was only 33%. However, highly toxic reactions to Rituximab such as pulmonary failure may occur and require delay or interrupting the use of this drug. High dose chemotherapy regimens followed by autologous stem-cell transplantation has offered clinical improvement similar to that found with the CHOP plus Rituximabn. However, only a small percentage of patients with IVBCL are young and healthy enough to receive this regimen. [5] Intravenous methotrexate may be a useful addition to the rituximab-CHOP regiment in individuals with central nervous system involvement. [18] [19]
The cutaneous variant, which comprises a small percentage of all IVBCL cases, occurs almost exclusively in females and younger individuals (median age 59 years) than the classical variant (median age 72 years). [5] Individuals present with lesions that are exclusively or greatly confined to the skin. [2] The clinical features of these lesions are similar to those described in the section on Presentation of the classical variant. Individuals with the cutaneous variant may have systemic symptoms but this occurs less frequently (30% of cases) than those in the classical variant (45% of cases). In general, cutaneous variant patients are in much better physical shape than those with other forms of IVBCL and have a better long-term prognosis. [5]
The diagnosis of IVL, cutaneous variant depends on finding the pathological picture in the skin as described for the classical variant except that the lesions occur exclusively or predominantly in the skin. Ideally, these pathological findings should be found in more than one skin site. [5] However, cutaneous involvement is frequently detected in a single site such as the hypervascular lesions of cherry hemangiomas and angiolipomas. [20]
Historically, individuals with the cutaneous variant survive significantly longer than that those with the classical variant (3 year overall survival 56% versus 22%). Early intervention in the cutaneous variant would appear to be highly desirable. [5] Virtually all reports on the treatment of the cutaneous variant were made before Rituximab was used to treat IVL. Historically, patients with localized disease obtained prolonged remission with conventional CHOP therapy. However, individuals with single cutaneous lesions were long‐term survivors: when treated with just radiation therapy or surgical removal, these single-lesion patients had prolonged remissions both at initial diagnosis and after relapse. In contrast, patients with multiple lesions had a far worse outcome after treatment with CHOP: they had an objective response in 86% of cases but nonetheless the majority relapsed within a year of treatment with and only a few being successfully managed with salvage chemotherapy. [21] Rituximab may improve the latter situation.[ citation needed ]
The hemophagocytic syndrome-associated variant of IVBCL is a very rare variant of IVBCL. Its previous name, intravascular large B-cell lymphoma, Asian variant, was recently changed to its current name by the world Health Organization, 2016. Unlike the classical and cutaneous variants, the hemophagocytic syndrome-associated variant presents with the hemophagocytic syndrome. This syndrome is characterized by bone marrow involvement, reduced numbers of circulating blood platelets [5] as well as the reduced levels of other circulating blood cells, [22] and enlarged liver and spleen. Less often, it is also associated with overt hemophagocytosis (i.e. the engulfment by non-malignant histiocytes of red blood cells, white blood cells, platelets, and their precursor cells that is most commonly found in the bone marrow and other tissues. [5] The syndrome often reflects excessive secretion of inflammatory cytokines and severe systemic inflammation similar to that seen in the cytokine storm syndrome. [2] In general, individuals present with a rapidly progressive disease (median time from onset to diagnosis~4 weeks, range 2–12 weeks). [12] Patients are often extremely ill [12] and experience multiple organ failures. [2]
The diagnosis of the intravascular large B-cell lymphoma, hemophagocytic syndrome-associated variant depends on the individual presenting with clinical and laboratory findings compatible with the hemphagocytic syndrome (see previous section) and on the histology of biopsied tissues of the bone marrow, spleen, liver, brain, or other organ that clinical and/or laboratory findings suggest are involved in the disease. Its histology is described in the Diagnosis section of the classical variant but also includes the presence of hemophagocytosis, i.e. the engulfment of red blood cells and/or other mature and immature blood cells. [5] Hemophagocytosis can also be found in sites removed from the intravascular lesions such as the cerebrospinal fluid in patients with central nervous system involvement. [22]
Prior to the use of rituximab, individuals with this variant generally followed a rapidly (i.e. weeks to months) fatal course even when treated with the CHOP regimen. However, addition of rituximab to the CHOP regimen appears to have improved the treatment of this disease. Intravenous methotrexate may be a useful addition to the rituximab-CHOP regiment in individuals with central nervous system involvement. [18] [19]
Three studies have examine gene mutations and gene expression abnormalities in IVNK/TL. A retrospective study of 25 patients identified numerous gene abnormalities including tumor-specific splicing alterations in oncogenes and tumor suppressor genes such as HRAS, MDM2, and VEGFA as well as premature termination mutations or copy number losses in a total of 15 splicing-regulator genes such as SF3B5 and TNPO3 . [23] A study of two patients with IVNKL identified mutations in genes that produce histone proteins ( HIST1H2BE, HIST1H2BN and H3F3A ), the histone deacetylase gene, HDAC5 , two genes that produce helicase proteins ( WRN and DDX3X ), two genes that make DNA methylation-related enzymes ( TET2 and DNMT1 ) and a gene in the SWI/SNF family of chromatin remodeling genes, ARID1A . [24] In a third study of a single patient, copy number analysis identified driver gene alterations in ARID1B, HACE1, and SMAD4 genes and gain of the SOX2 gene. [8] While further studies are needed before conclusions can be made, one or more of these gene abnormalities may contribute to the development and/or progression of IVNK/TL.[ citation needed ]
The malignant NK and T cells that accumulate within the vascular of individuals with IVNK/TL are usually infected with the Epstein–Barr virus (EBV). This suggests that most IVNK/TL cases are examples of the Epstein-Barr virus-associated lymphoproliferative diseases and, like these diseases, are EBV-driven. [8] About 95% of the world's population is infected with EBV. During the initial infection, the virus may cause infectious mononucleosis, only minor non-specific symptoms, or no symptoms. Regardless of this, the virus enters a latency phase and the infected individual becomes a lifetime asymptomatic carrier of EBV. Weeks, months, years, or decades thereafter, a small percentage of these carriers develop an EBV-associated lymphoproliferative disease, [25] [26] including in extremely rare cases IVNK/TL. [8] EBV is well known to infect NK- and T-cells, to express some of its genes that promote the survival and proliferation of the cells it infects, and thereby to cause various and far more common NK- and T-cell lymphomas. [27] It seems likely that the virus acts similarly to cause IVNK/TL. [8] IVNK/TL may differ from the other types of NK- and T-cell lymphomas which EBV produces because its NK- and T-cells and nearby endothelial cells have defects in the expression of proteins required for the NK/T-cells to pass through the endothelium and into the surrounding tissues (see above section on the Pathopysiology IVBCL). [28]
Individuals (age range 23–81 years [8] ) with IVNK/TL typically have a rapidly progressive disease. They commonly present with skin lesions, less commonly symptoms due to central nervous system involvement, and in a minority of cases symptoms due to the involvement of the bone marrow, liver, kidneys, ovaries, and/or cervix. [1] They often show signs of a disseminated disease such as fever, weight loss, night sweats, arthralgias, jaundice, decreased numbers of circulating red blood cells, white blood cells, and/or platelets, bone marrow involvement as determined by biopsy, and signs/symptoms of multiple organ involvement. [8]
The diagnosis of IVNK/TL depends upon obtaining histology findings in the skin and/or other involved tissue that resembles that seen in IVBCL except that the malignant lymphocytes are not B-cells but rather: 1) NK-cells as evidenced by their expression of NK-cell selective marker proteins (e.g. CD3e, CD2, CD30, CD43, CD56, and/or CD79), expression of granule-bound enzymes (e.g. granzyme B), [8] and expression of EBV proteins (e.g. Epstein–Barr virus latent membrane protein 1 [8] and EBV-produced small RNAs [1] ); but not the expression of B-cell (e.g. CD20, CD79a, and Pax5) or cytotoxic T cell marker proteins; [8] and 2) cytotoxic T-cell lymphoma as evidenced by the neoplastic cells' expression of T-cell co-receptor proteins (e.g. CD3, CD4, and/or CD8) as well as EBV marker proteins and/or small RNAs but usually not B-cell or NK-cell marker proteins. [9]
Patients with IVNK/TL have been treated with various chemotherapy regimens, particularly CHOP or, less commonly, hyperCVAD. Rare patients have been treated with chemotherapy followed by hematopoietic stem cell transplantation or chemotherapy plus a proteasome inhibitor, bortezomib. In general, patients have responded poorly to treatment, have short (i.e. up to 12 months) survival times regardless of the chemotherapy regimen used. [8] [9] [29] [30] Rituximab does not target NK- or T-cells and therefore is not used to treat IVNK/TL.[ citation needed ]
Burkitt lymphoma is a cancer of the lymphatic system, particularly B lymphocytes found in the germinal center. It is named after Denis Parsons Burkitt, the Irish surgeon who first described the disease in 1958 while working in equatorial Africa. The overall cure rate for Burkitt lymphoma in developed countries is about 90%, and it is worse in low-income countries. Burkitt lymphoma is uncommon in adults, in whom it has a worse prognosis.
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.
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 in the germinal centers of lymphoid tissues such as lymph nodes. The cancerous cells in FL typically form follicular or follicle-like structures 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.
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.
Aggressive NK-cell leukemia is a disease with an aggressive, systemic proliferation of natural killer cells and a rapidly declining clinical course.
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.
X-linked lymphoproliferative disease is a lymphoproliferative disorder, usually caused by SH2DIA gene mutations in males. XLP-positive individuals experience immune system deficiencies that render them unable to effectively respond to the Epstein-Barr virus (EBV), a common virus in humans that typically induces mild symptoms or infectious mononucleosis (IM) in patients. There are two currently known variations of the disorder, known as XLP1 and XLP2. XLP1 is estimated to occur in approximately one in every million males, while XLP2 is rarer, estimated to occur in one of every five million males. Due to therapies such as chemotherapy and stem cell transplants, the survival rate of XLP1 has increased dramatically since its discovery in the 1970s.
Enteropathy-associated T-cell lymphoma (EATL), previously termed enteropathy-associated T-cell lymphoma, type I and at one time termed enteropathy-type T-cell lymphoma (ETTL), is a complication of coeliac disease in which a malignant T-cell lymphoma develops in areas of the small intestine affected by the disease's intense inflammation. While a relatively rare disease, it is the most common type of primary gastrointestinal T-cell lymphoma.
Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy. It was initially regarded as a form of lymphocyte-derived cutaneous lymphoma and alternatively named CD4+CD56+ hematodermic tumor, blastic NK cell lymphoma, and agranular CD4+ NK cell leukemia. Later, however, the disease was determined to be a malignancy of plasmacytoid dendritic cells rather than lymphocytes and therefore termed blastic plasmacytoid dendritic cell neoplasm. In 2016, the World Health Organization designated BPDCN to be in its own separate category within the myeloid class of neoplasms. It is estimated that BPDCN constitutes 0.44% of all hematological malignancies.
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.
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.
Plasmablastic lymphoma (PBL) is a type of large B-cell lymphoma recognized by the World Health Organization (WHO) in 2017 as belonging to a subgroup of lymphomas termed lymphoid neoplasms with plasmablastic differentiation. The other lymphoid neoplasms within this subgroup are: plasmablastic plasma cell lymphoma ; primary effusion lymphoma that is Kaposi's sarcoma-associated herpesvirus positive or Kaposi's sarcoma-associated Herpesvirus negative; anaplastic lymphoma kinase-positive large B-cell lymphoma; and human herpesvirus 8-positive diffuse large B-cell lymphoma, not otherwise specified. All of these lymphomas are malignancies of plasmablasts, i.e. B-cells that have differentiated into plasmablasts but because of their malignant nature: fail to differentiate further into mature plasma cells; proliferate excessively; and accumulate in and injure various tissues and organs.
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.
Mosquito bite allergies, also termed hypersensitivity to mosquito bites, are excessive reactions of varying severity to mosquito bites. They are allergic hypersensitivity reactions caused by the non-toxic allergenic proteins contained in the saliva injected by a female mosquito at the time it takes its blood meal, and are not caused by any toxin or pathogen. By general agreement, mosquito bite allergies do not include the ordinary wheal and flare responses to these bites although these reactions are also allergic in nature. Ordinary mosquito bite allergies are nonetheless detailed here because they are the best understood reactions to mosquito bites and provide a basis for describing what is understood about them.
Natural killer cell enteropathy, also termed NK cell enteropathy (NKCE), and a closely related disorder, lymphomatoid gastropathy (LG), are non-malignant diseases in which one type of lymphocyte, the natural killer cell, proliferates excessively in the gastrointestinal tract. This proliferation causes red, sore-like spots, raised lesions, erosions, and ulcers in the mucosal layer surrounding the GI tract lumen. Both disorders cause either no or only vague symptoms of GI tract disturbances such as nausea, vomiting, and bleeding.
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.
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.