Natural killer cell enteropathy

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Natural killer cell enteropathy
Other namesNK cell enteropathy, lymphomatoid gastropathy
Specialty Hematology and Oncology
TypesNK cell enteropathy (anywhere in GI tract), lymphomatoid gsatroathy (restricted to stomach)
CausesNK cell proliferation due to unknown causes
Differential diagnosis Mimics malignant lymphomas
TreatmentNot necessary
Prognosis Good

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 (i.e. NK cell), proliferates excessively in the gastrointestinal tract (GI tract). [1] 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. [2]

Contents

In 2006, a persistent but apparently benign disease that involved the proliferation of NK cells at multiple sites throughout the intestines was described. This disorder appeared similar to and easily mistaken for a highly malignant disease, extranodal NK/T-cell lymphoma, nasal type. [3] In 2010, a similarly non-malignant disorder that involved the proliferation of NK cells in the stomach was described. The disease mimicked gastrointestinal lymphomas. [4] Since these first descriptions, several case series and case reports have been published on these enteropathies. [5]

The two NK cell proliferation diseases have been termed NK cell enteropathy and lymphomatoid gastropathy with NKCE being seen mostly in the United States and Korea and LG being seen mostly in Japan. [6] Besides this geographical difference, the only other critical difference between the two diseases is that the lesions in NKCE occur in the small intestine, colon, stomach, and/or esophagus while those of LG are limited to the stomach. [7] Since the pathophysiological features of the two diseases are virtually identical, NKCE and LG are now commonly viewed as manifestations of the same disease. [2] [5] [7] [6] [8]

Only 36 patients with NKCE or LG have been reported as of January 2019. [5] Nonetheless, these diseases are emerging as important clinical entities because they 1) are newly described and likely to be diagnosed more often as they become better known and 2) have been mistaken for, and treated as, various types of pre-malignant and malignant lymphomas of the GI tract. Given the radical differences in the prognoses and treatments of NKCE and LG compared to the lymphomas that they can mimic, the evaluation of many lymphocyte-proliferating disorders of the GI tract must consider and rule out the possibility that they are NKCE or LG rather than a pre-malignant disorder or malignant lymphoma. [2]

Presentation

Most cases of NKCE [9] and LG [5] have been reported in middle-aged or older individuals. Patients diagnosed with NKCE (medium age 46 years) have presented with vague abdominal pain, indigestion, vomiting, diarrhea, [5] constipation, [6] weight loss, anemia, and/or GI bleeding. [5] Two patients complained of biliary colic (i.e. gallbladder pain) and were found to have typical lesions of NKCE in their cystic ducts. [5] These two cases indicate that NKCE involvement is not totally limited to the alimentary canal. Three of 15 individuals diagnosed with NKCE disease reported no symptoms, their disease being found on endoscopy conducted for screening purposes. Typically, patients diagnosed with LG (medium age 58 years) have been asymptomatic at presentation with their disease being detected during GI tract examinations done for other reasons. Three of twenty patients diagnosed with LG complained of pain or discomfort in the upper abdominal region. Symptomatic individuals with either disease generally have a long history of persistent or intermittent symptoms. [5]

Pathophysiology

NK cells normally occupy the GI tract where they contribute to innate immunity [7] by becoming active in killing pathogen-infected and cancerous cells. [10] The proliferating lymphocytes in NKCE and LG express CD56 and CD7 proteins on their cell surface membrane, CD3γ protein in their cytoplasm, and granzyme B, perforin, and T-cell intracellular antigen-1 cytotoxic proteins within their cytoplasmic granules. This pattern of protein expression identifies these cells as NK cells that, because of their expression of the cytotoxic granule-bound proteins, have been activated. [7] However, the cause(s) for the activation of these cells as wells as for their rapid proliferation to produce NKCE [5] and LG [8] is unknown. To date, no evidence of NK cell clonality (i.e. cells developing from a single precursor) or for these cells to bear gene mutations or chromosome abnormalities have been reported in NKCE or LG. These findings help distinguish LB and NKCE from many lymphomas and support the conclusion that neither disease is malignant. [6] The NK cells in LG and NKCE are not infected with the Epstein-Barr virus (EBV), as evidenced by their failure to express this virus's latency proteins and latency ncRNAs. This finding indicates that EBV is not the cause for the NK cell activation and excessive proliferation seen in NKCE and LG and distinguishes these diseases from malignant diseases they can mimic such as extranodal NK/T-cell lymphoma, nasal type. [5] In isolated reports, LG has occurred in individuals with Helicobacter pylori infection of the stomach or a history of stomach cancer, [7] while NKCE has been reported to occur in patients with gluten sensitivity [10] or circulating anti-gliadin antibodies. Both of the latter conditions are associated with the development of GI tract lymphomas. [5] However, the relationship of any of these findings to the etiology of LB and NKCE is unclear. [5]

Histology

Biopsies of NKCE tissues reveal atypical medium to large lymphocytes identified by immunohistochemistry to be NK cells that are multiplying at a moderately rapid rate [9] and that lack evidence of being infected by the Epstein-Barr virus. [2] These cells are located primarily in the lamina propria, i.e. loose connective tissue lying just below the epithelium lining the GI tract. There is generally little invasion of these cells into the epithelium, submucosa, or glands of the GI tract, and the lesions almost always show a complete absence of vascular injury due to invasion by these cells. [9] The lesions in LG closely resemble those of NKCE. [5]

Diagnosis

The diagnoses of NKCE and LG depends on clinical and pathological findings indicating that the two diseases: a) are indolent and non-malignant; b) usually manifested by mild, vague, or no symptoms; c) localize to the GI tract without involvement of the head, neck, or organs such as the liver and spleen; d) consist of one or more lesions localized primarily to the lamina propria of the esophagus, stomach, small intestine, and/or large intestine (for NKCE} or to the stomach (for LG); and e) involve lesions which contain medium-to large-sized, atypical, and non-clonal lymphocytes that are activated NK cells (see Pathophysiology section) which proliferate at moderately rapid rates (as gauged by, e.g. analysis of their Ki-67 protein levels), lack evidence of Epstein-Barr virus infection, gene mutations, or chromosome abnormalities, and show little evidence of centering around, and destroying, blood vessels. [9]

Differential diagnosis

In early studies, aggressive chemotherapy with or without bone marrow translanton and gastric resections were used to treat NKCE and LG, respectively, based on the assumptions that these diseases were malignant. [5] Since there was no evidence that these treatments influenced the underlying disease [5] [6] and since NKCE and LG are essentially benign disorders, they must be distinguished from the malignant diseases which they mimic. [5] Three malignant or potentially premalignant diseases which can closely resemble NKCE and LG along with some clinical and laboratory findings which differentiate them from NKCE and LT are:

Other diseases which NKCE and LG may superficially resemble and require consideration as being in their differential diagnoses include: peripheral T-cell lymphoma not otherwise specified, T cell lymphomas that consist of mature T cells and occur in the GI tact, [10] MALT lymphoma of the stomach, [13] and other types of stomach lymphomas. [7]

Treatment

Patients with NKCE or LG should be treated for symptom relief but, as currently recommended, not for the underlying NK cell proliferative disease. Regular follow-ups that include repeated endoscopic analyses of their GI tracts and tests for the spreading of the disease to other organs are recommended to insure the original diagnosis is correct. [2] [6] [9] [13]

Prognosis

NKCE and LG usually follow a persistent or regressing-relapsing coarse but uncommonly spontaneously relapses without a recurrence even in cases that have been mistreated with chemotherapy, bone marrow transplantation, or gastric resection. Patients with LG are less likely to have persistent or regressing-relapsing coarse. Symptoms of the disease usually remain vague and mild. [5]

Related Research Articles

<span class="mw-page-title-main">Lymphoma</span> Hematologic cancer that affects lymphocytes

Lymphoma is a group of blood and lymph tumors that develop from lymphocytes. The name typically refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include enlarged lymph nodes, fever, drenching sweats, unintended weight loss, itching, and constantly feeling tired. The enlarged lymph nodes are usually painless. The sweats are most common at night.

Post-transplant lymphoproliferative disorder (PTLD) is the name given to a B cell proliferation due to therapeutic immunosuppression after organ transplantation. These patients may develop infectious mononucleosis-like lesions or polyclonal polymorphic B-cell hyperplasia. Some of these B cells may undergo mutations which will render them malignant, giving rise to a lymphoma.

<span class="mw-page-title-main">Tumors of the hematopoietic and lymphoid tissues</span> Medical condition

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.

<span class="mw-page-title-main">Follicular lymphoma</span> Medical condition

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.

Enteropathy refers to any pathology of the intestine. Although enteritis specifically refers to an inflammation of the intestine, and is thus a more specific term than "enteropathy", the two phrases are sometimes used interchangeably.

<span class="mw-page-title-main">Primary effusion lymphoma</span> Medical condition

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.

<span class="mw-page-title-main">T-cell lymphoma</span> Medical condition

T-cell lymphoma is a rare form of cancerous lymphoma affecting T-cells. Lymphoma arises mainly from the uncontrolled proliferation of T-cells and can become cancerous.

<span class="mw-page-title-main">Gastric lymphoma</span> Medical condition

Primary gastric lymphoma is an uncommon condition, accounting for less than 15% of gastric malignancies and about 2% of all lymphomas. However, the stomach is a very common extranodal site for lymphomas. It is also the most common source of lymphomas in the gastrointestinal tract.

<span class="mw-page-title-main">Intravascular lymphomas</span> Medical condition

Intravascular lymphomas (IVL) are rare cancers in which malignant lymphocytes proliferate and accumulate within blood vessels. Almost all other tyes 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.

<span class="mw-page-title-main">Diffuse large B-cell lymphoma</span> Type of blood cancer

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.

Lymphomatoid granulomatosis (LYG or LG) is a very rare lymphoproliferative disorder first characterized in 1972. Lymphomatoid means lymphoma-like and granulomatosis denotes the microscopic characteristic of the presence of granulomas with polymorphic lymphoid infiltrates and focal necrosis within it.

<span class="mw-page-title-main">Enteropathy-associated T-cell lymphoma</span> Complication of coeliac disease

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.

<span class="mw-page-title-main">Marginal zone B-cell lymphoma</span> Group of lymphomas

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.

<span class="mw-page-title-main">Extranodal NK/T-cell lymphoma, nasal type</span> Medical condition

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.

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Indolent T cell lymphoproliferative disorder of the gastrointestinal tract or Indolent T cell lymphoproliferative disorder of the GI tract (ITCLD-GT) is a rare and recently recognized disorder in which mature T cell lymphocytes accumulation abnormally in the gastrointestinal tract. This accumulation causes various lesions in the mucosal layer lining the GI tract. Individuals with ITCLD-GT commonly complain of chronic GI tract symptoms such as nausea, vomiting, diarrhea, abdominal pain, and rectal 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.

Duodenal-type follicular lymphoma (DFL) is a form of lymphoma in which certain lymphocyte types, the B-cell-derived centrocytes and centroblasts, form lymph node follicle-like structures principally in the duodenum and other parts of the small intestine. It is an indolent disease which on rare occasions progresses to a more aggressive lymphoma that spreads beyond these originally involved sites.

Helicobacter heilmannii sensu lato refers to a group of bacterial species within the Helicobacter genus. The Helicobacter genus consists of at least 40 species of spiral-shaped flagellated, Gram-negative bacteria of which the by far most prominent and well-known species is Helicobacter pylori. H. pylori is associated with the development of gastrointestinal tract diseases such as stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers that are not lymphomas, and various subtypes of extranodal marginal zone lymphomas, e.g. those of the stomach, small intestines, large intestines, and rectumn. H. pylori has also been associated with the development of bile duct cancer and has been associated with a wide range of other diseases although its role in the development of many of these other diseases requires further study.

References

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  3. ↑ Vega F, Chang CC, Schwartz MR, Preti HA, Younes M, Ewton A, Verm R, Jaffe ES (April 2006). "Atypical NK-cell proliferation of the gastrointestinal tract in a patient with antigliadin antibodies but not celiac disease". The American Journal of Surgical Pathology. 30 (4): 539–44. doi:10.1097/00000478-200604000-00017. PMID   16625103. S2CID   29115000.
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