Most people affected by primary gastric lymphoma are over 60 years old. Symptoms include epigastric pain, early satiety, fatigue and weight loss.

Primary gastric lymphoma (lymphoma that originates in the stomach itself) 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 (lymphomas originating somewhere else with metastasis to stomach). It is also the most common source of lymphomas in the gastrointestinal tract.

Lymphoma may present with certain nonspecific symptoms; if the symptoms are persistent, an evaluation to determine their cause, including possible lymphoma, should be undertaken.

- Lymphadenopathy or swelling of lymph nodes, is the primary presentation in lymphoma.

- B symptoms (systemic symptoms) – can be associated with both Hodgkin lymphoma and non-Hodgkin lymphoma. They consist of:

- Fever

- Night sweats

- Weight loss

- Other symptoms:

- Loss of appetite or anorexia

- Fatigue

- Respiratory distress or dyspnea

- Itching

Individuals with this type of cancer experience almost no symptoms at all.

- Painless Lymphadenopathy

- Fatigue

- Weight loss

- Fevers

- Night sweat

The signs and symptoms of non-Hodgkin's lymphoma vary depending upon its location within the body. Symptoms include enlarged lymph nodes, fever, night sweats, weight loss, and feeling tired. Other symptoms may include bone pain, chest pain, or itchiness. Some forms are slow growing while others are fast growing. Enlarged lymph nodes may cause lumps to be felt under the skin when they are close to the surface of the body. Lymphomas in the skin may also result in lumps, which are commonly itchy, red or purple. Lymphomas in the brain can cause weakness, seizures, problems with thinking and personality changes.

Most individuals with non-gastric MALT have no symptoms

- Symptoms depend on where the cancer originates:

- Mass in the salivary gland

- Redness and sensitivity of the eye

- Mass in the thyroid

- Problems swallowing

- Cough

- Shortness of breath

- Fever

- Weight loss

- Red-brown discoloration of the skin

"MALT lymphoma" is an often multifocal disease in the organ of origin and is frequently macroscopically indistinguishable from other disease processes in the GI tract. Endoscopy is key to diagnosing "MALT lymphoma", with multiple biopsies of the visible lesions required, as well as samples of macroscopically normal tissue, termed gastric mapping. Histologically, there is expansion of the marginal zone compartment with development of sheets of neoplastic small lymphoid cells. The morphology of the neoplastic cells is variable with small mature lymphocytes, cells resembling centrocytes (centrocyte like cells), or marginal zone/monocytoid B cells. Plasmacytoid or plasmacytic differentiation is frequent. Lymphoid follicles are ubiquitous to "MALT lymphoma" but may be indistinct as they are often overrun or colonized by the neoplastic cells. Large transformed B cells are present scattered among the small cell population. If these large cells are present in clusters or sheets, a diagnosis of associated large B-cell lymphoma should be considered. A characteristic feature of MALT lymphoma is the presence of neoplastic cells within epithelial structures with associated destruction of the glandular architecture to form lymphoepithelial lesions.

"MALT lymphoma" may be difficult to distinguish from reactive infiltrates, and in some cases, multiple endoscopies are required before a confident diagnosis is reached. The Wotherspoon score, which grades the presence of histological features associated with "MALT lymphoma", is useful in expressing confidence in diagnosis at presentation.

Immunohistochemistry can be used to help distinguish "MALT lymphoma" from other small B-cell NHLs. B-cell-associated antigens such as CD19, CD20, CD22, and CD79a are usually expressed. In contrast to small lymphocytic lymphoma and MCL, staining for CD5 is usually negative, and these lymphomas can be further distinguished with CD23 (positive in small lymphocytic lymphoma) and CyclinD1 (positive in MCL).

Patients with Hodgkin's lymphoma may present with the following symptoms:

- Lymph nodes: the most common symptom of Hodgkin's is the painless enlargement of one or more lymph nodes, or lymphadenopathy. The nodes may also feel rubbery and swollen when examined. The nodes of the neck and shoulders (cervical and supraclavicular) are most frequently involved (80–90% of the time, on average). The lymph nodes of the chest are often affected, and these may be noticed on a chest radiograph.

- Itchy skin

- Night sweats

- Unexplained weight loss

- Splenomegaly: enlargement of the spleen occurs in about 30% of people with Hodgkin's lymphoma. The enlargement, however, is seldom massive, and the size of the spleen may fluctuate during the course of treatment.

- Hepatomegaly: enlargement of the liver, due to liver involvement, is present in about 5% of cases.

- Hepatosplenomegaly: the enlargement of both the liver and spleen caused by the same disease.

- Pain following alcohol consumption: classically, involved nodes are painful after alcohol consumption, though this phenomenon is very uncommon, occurring in only two to three percent of people with Hodgkin's lymphoma, thus having a low sensitivity. On the other hand, its positive predictive value is high enough for it to be regarded as a pathognomonic sign of Hodgkin lymphoma. The pain typically has an onset within minutes after ingesting alcohol, and is usually felt as coming from the vicinity where there is an involved lymph node. The pain has been described as either sharp and stabbing or dull and aching.

- Back pain: nonspecific back pain (pain that cannot be localised or its cause determined by examination or scanning techniques) has been reported in some cases of Hodgkin's lymphoma. The lower back is most often affected.

- Red-coloured patches on the skin, easy bleeding and petechiae due to low platelet count (as a result of bone marrow infiltration, increased trapping in the spleen etc.—i.e. decreased production, increased removal)

- Systemic symptoms: about one-third of patients with Hodgkin's disease may also present with systemic symptoms, including low-grade fever; night sweats; unexplained weight loss of at least 10% of the patient's total body mass in six months or less, itchy skin (pruritus) due to increased levels of eosinophils in the bloodstream; or fatigue (lassitude). Systemic symptoms such as fever, night sweats, and weight loss are known as B symptoms; thus, presence of fever, weight loss, and night sweats indicate that the patient's stage is, for example, 2B instead of 2A.

- Cyclical fever: patients may also present with a cyclical high-grade fever known as the Pel-Ebstein fever, or more simply "P-E fever". However, there is debate as to whether the P-E fever truly exists.

- Nephrotic syndrome can occur in individuals with Hodgkin's lymphoma and is most commonly caused by minimal change disease.

MALT lymphoma (MALToma) is a form of lymphoma involving the mucosa-associated lymphoid tissue (MALT), frequently of the stomach, but virtually any mucosal site can be afflicted. It is a cancer originating from B cells in the marginal zone of the MALT, and is also called extranodal marginal zone B cell lymphoma.

The symptoms of AIDS-related lymphoma can include: weight loss, fever, and night sweats.

Currently, Burkitt lymphoma can be divided into three main clinical variants: the endemic, the sporadic, and the immunodeficiency-associated variants.

- The endemic variant (also called "African variant") most commonly occurs in children living in malaria endemic regions of the world (e.g., equatorial Africa, Brazil, and Papua New Guinea). Epstein-Barr virus (EBV) infection is found in nearly all patients. Chronic malaria is believed to reduce resistance to EBV, allowing it to take hold. The disease characteristically involves the jaw or other facial bone, distal ileum, cecum, ovaries, kidney, or breast.

- The sporadic type of Burkitt lymphoma (also known as "non-African") is the most common variant found in places where malaria is not holoendemic. The tumor cells have a similar appearance to the cancer cells of classical endemic Burkitt lymphoma. Sporadic lymphomas are rarely associated with the Epstein–Barr virus. Non-Hodgkin lymphoma, which includes Burkitt's, accounts for 30–50% of childhood lymphoma. The jaw is less commonly involved, compared to the endemic variant. The ileocecal region is the common site of involvement.

- Immunodeficiency-associated Burkitt lymphoma is usually associated with HIV infection or occurs in the setting of post-transplant patients who are taking immunosuppressive drugs. Burkitt lymphoma can be one of the diseases associated with the initial manifestation of AIDS.

By morphology (i.e., microscopic appearance) or immunophenotype, it is almost impossible to differentiate these three clinical variants. Immunodeficiency-associated Burkitt lymphoma may demonstrate more plasmacytic appearance or more pleomorphism, but these features are not specific.

Lymphoma is a group of blood cancers that develop from lymphocytes (a type of white blood cell). The name often refers to just the cancerous versions rather than all such tumors. 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.

There are dozens of subtypes of lymphomas. The two main categories of lymphomas are Hodgkin's lymphomas (HL) and the non-Hodgkin lymphomas (NHL). The World Health Organization (WHO) includes two other categories as types of lymphoma: multiple myeloma and immunoproliferative diseases. About 90% of lymphomas are non-Hodgkin lymphomas. Lymphomas and leukemias are a part of the broader group of tumors of the hematopoietic and lymphoid tissues.

Risk factors for Hodgkin lymphoma include infection with Epstein–Barr virus and a history of the disease in the family. Risk factors for common types of non-Hodgkin lymphomas include autoimmune diseases, HIV/AIDS, infection with human T-lymphotropic virus, immunosuppressant medications, and some pesticides. Eating large amounts of red meat and tobacco smoking may also increase the risk. Diagnosis, if enlarged lymph nodes are present, is usually by lymph node biopsy. Blood, urine, and bone marrow testing may also be useful in the diagnosis. Medical imaging may then be done to determine if and where the cancer has spread. Lymphoma most often spreads to the lungs, liver, and brain.

Treatment may involve one or more of the following: chemotherapy, radiation therapy, targeted therapy, and surgery. In some non-Hodgkin lymphomas, an increased amount of protein produced by the lymphoma cells causes the blood to become so thick that plasmapheresis is performed to remove the protein. Watchful waiting may be appropriate for certain types. The outcome depends on the subtype with some being curable and treatment prolonging survival in most. The five-year survival rate in the United States for all Hodgkin lymphoma subtypes is 85%, while that for non-Hodgkin lymphomas is 69%. Worldwide, lymphomas developed in 566,000 people in 2012 and caused 305,000 deaths. They make up 3–4% of all cancers, making them as a group the seventh-most common form. In children, they are the third-most common cancer. They occur more often in the developed world than the developing world.

The cancer is classified into low and high grade types. Classification is also based on location. The four location types are multicentric, mediastinal, gastrointestinal, and extranodal (involving the kidney, central nervous system, skin, heart, or eye). Multicentric lymphoma, the most common type (by greater than 80 percent), is found in the lymph nodes, with or without involvement in the liver, spleen, or bone marrow. Mediastinal lymphoma occurs in the lymph nodes in the thorax and possibly the thymus. Gastrointestinal lymphoma occurs as either a solitary tumor or diffuse invasion of the stomach or intestines, with or without involvement in the surrounding lymph nodes, liver or spleen. Classification is further based on involvement of B-lymphocytes or T-lymphocytes. Approximately 70 percent are B-cell lymphoma. Cutaneous lymphoma can be classified as epitheliotropic (closely conforming to the epidermis) or non-epitheliotropic. The epitheliotropic form is typically of T-cell origin and is also called mycosis fungoides. The non-epitheliotropic form is typically of B-cell origin.

Follicular lymphoma is a type of blood cancer. It is the most common of the indolent (slow-growing) non-Hodgkin's lymphomas, and the second-most-common form of non-Hodgkin's lymphomas overall. It is defined as a lymphoma of follicle center B-cells (centrocytes and centroblasts), which has at least a partially follicular pattern. It is positive for the B-cell markers CD10, CD19, CD22, and usually CD20, but almost always negative for CD5.

There are several synonymous and obsolete terms for this disease, such as CB/CC lymphoma (Centroblastic and Centrocytic lymphoma), nodular lymphoma and Brill-Symmers Disease.

The majority of thyroid lymphomas are non–Hodgkin's B-cell lymphomas; the rest exhibit properties of T-cell lymphomas .

- Diffuse large B-cell lymphoma with marginal zone

- Diffuse large B-cell lymphoma without marginal zone

- Marginal zone В-cell lymphoma of mucosa-associated lymphoid tissue (MALT)

- Follicular lymphoma

Non-Hodgkin lymphoma (NHL) is a group of blood cancers that includes all types of lymphoma except Hodgkin's lymphomas. Symptoms include enlarged lymph nodes, fever, night sweats, weight loss, and tiredness. Other symptoms may include bone pain, chest pain, or itchiness. Some forms are slow growing while others are fast growing.

Lymphomas are types of cancer that develop from lymphocytes, a type of white blood cell. Risk factors include poor immune function, autoimmune diseases, "Helicobacter pylori" infection, hepatitis C, obesity, and "Epstein-Barr virus" infection. The World Health Organization (WHO) classifies lymphomas into five major groups, including one for Hodgkin's lymphoma. Within the four groups for NHL there are over 60 specific types of lymphoma. Diagnosis is by examination of a bone marrow or lymph node biopsy. Medical imaging is done to help with cancer staging.

Treatment depends on whether the lymphoma is slow or fast growing and if it is in one area or many areas. Treatments may include chemotherapy, radiation, immunotherapy, targeted therapy, stem cell transplantation, surgery, or watchful waiting. If the blood becomes overly thick due to antibodies, plasmapheresis may be used. Radiation and some chemotherapy, however, increase the risk of other cancers, heart disease or nerve problems over the subsequent decades.

In 2015 about 4.3 million people had non-Hodgkin lymphoma and 231,400 died. In the United States 2.1% of people are affected at some point in their life. The most common age of diagnosis is between 65 and 75 years old. The percentage of people who survive five years in the United States is 71%.

General signs and symptoms include depression, fever, weight loss, loss of appetite, loss of hair or fur and vomiting. Lymphoma is the most common cancerous cause of hypercalcemia (high blood calcium levels) in dogs. It can lead to the above signs and symptoms plus increased water drinking, increased urination, and cardiac arrhythmias. Hypercalcemia in these cases is caused by secretion of parathyroid hormone-related protein.

Multicentric lymphoma presents as painless enlargement of the peripheral lymph nodes. This is seen in areas such as under the jaw, the armpits, the groin, and behind the knees. Enlargement of the liver and spleen causes the abdomen to distend. Mediastinal lymphoma can cause fluid to collect around the lungs, leading to coughing and difficulty breathing. Hypercalcemia is most commonly associated with this type.

Gastrointestinal lymphoma causes vomiting, diarrhea, and melena (digested blood in the stool). Low serum albumin levels and hypercalcemia can also occur.

Lymphoma of the skin is an uncommon occurrence. The epitheliotropic form typically appears as itchy inflammation of the skin progressing to nodules and plaques.

The non-epitheliotropic form can have a wide variety of appearances, from a single lump to large areas of bruised, ulcerated, hairless skin. The epitheliotropic form must be differentiated from similar appearing conditions such as pemphigus vulgaris, bullous pemphigoid, and lupus erythematosus.

Signs for lymphoma in other sites depend on the location. Central nervous system involvement can cause seizures or paralysis. Eye involvement, seen in 20 to 25 percent of cases, can lead to glaucoma, uveitis, bleeding within the eye, retinal detachment, and blindness. Lymphoma in the bone marrow causes anemia, low platelet count, and low white blood cell count.

Extranodal NK/T-cell lymphoma, nasal type which was known as angiocentric lymphoma in the REAL classification, and also as nasal-type NK lymphoma, NK/T-cell lymphoma, and polymorphic/malignant midline reticulosis is a cutaneous condition which in Korea is reported to be the most common form of cutaneous lymphoma after mycosis fungoides.

Extranodal NK-T-cell lymphoma is a type of lymphoma.

It is called "extranodal" to emphasize that the location is typically not in the lymph node, and is sometimes further qualified as "nasal type". The nasal cavity, nasopharynx and upper aerodigestive tract are often involved, although extranasal presentations do occur (skin, gastrointestinal tract, eye, testis, lung, soft tissue). There is a strong association with Epstein–Barr virus.

The NCCN guidelines recommend either high-dose radiotherapy alone for stage I without high risk features, or concurrent chemoradiotherapy for stage I and II with either of two regimens. Asparaginase containing regimens have been used in advanced stage disease.

As other thyroid lesions, thyroid lymphoma affects predominantly females over 70 years of age with a history of Hashimoto's thyroiditis. Thus, Hashimoto's thyroiditis is considering as risk factor for thyroid lymphoma development.

The thyroid lymphoma manifests as rapidly enlarging neck mass causing respiratory difficulty. On physical examination, patients usually exhibit a firm thyroid and lymphadenopathy.

There are two main types of intraocular lymphomas: primary central nervous system involvement (PCNSL) and primary central nervous system with ocular involvement (PCNSLO). The difference between PCNSL and PCNSLO is that PNSCL involves the central nervous system, while PCNSLO does not. 56-86% of orbital lymphomas are classified PCNSL and 15-25% are classified PCNSLO.

PCNSLO is common in people who are severely immunosuppressed.

Symptoms of this form of ocular lymphoma include painless decreased vision, sensitivity to light, a red eye, and floaters. Diagnosis is difficult due to its gradual onset and the fact that the symptoms are the same as other diseases.

PCNSLO is usually bilateral, but sometimes grows unevenly. Like other metastatic tumors of the eye, it is usually confined to the choroid.

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.

B-cell lymphomas include both Hodgkin's lymphomas and most non-Hodgkin lymphomas. They are typically divided into low and high grade, typically corresponding to indolent (slow-growing) lymphomas and aggressive lymphomas, respectively. As a generalisation, indolent lymphomas respond to treatment and are kept under control (in remission) with long-term survival of many years, but are not cured. Aggressive lymphomas usually require intensive treatments, with some having a good prospect for a permanent cure.

Prognosis and treatment depends on the specific type of lymphoma as well as the stage and grade. Treatment includes radiation and chemotherapy. Early-stage indolent B-cell lymphomas can often be treated with radiation alone, with long-term non-recurrence. Early-stage aggressive disease is treated with chemotherapy and often radiation, with a 70-90% cure rate. Late-stage indolent lymphomas are sometimes left untreated and monitored until they progress. Late-stage aggressive disease is treated with chemotherapy, with cure rates of over 70%.

Burkitt lymphoma is a cancer of the lymphatic system, particularly B lymphocytes found in the germinal center. It is named after Denis Parsons Burkitt, a surgeon who first described the disease in 1958 while working in equatorial Africa.

AIDS-related lymphoma describes lymphomas occurring in patients with acquired immunodeficiency syndrome (AIDS).

A lymphoma is a type of cancer arising from lymphoid cells. In AIDS, the incidences of non-Hodgkin's lymphoma, primary cerebral lymphoma and Hodgkin's disease are all increased. There are three different varieties of AIDS-related lymphoma: Diffuse large B-cell lymphoma, B-cell immunoblastic lymphoma, and Burkitt's lymphoma (small non-cleaved cell lymphoma).

There are numerous kinds of lymphomas involving B cells. The most commonly used classification system is the WHO classification, a convergence of more than one, older classification systems.

Aggressive lymphoma is a type of lymphoma that grows and spreads quickly, and has severe symptoms. It is seen frequently in patients who are HIV-positive (AIDS-related lymphoma). Also called intermediate-grade lymphoma and high-grade lymphoma.