Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). The name typically 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. The two main categories of lymphomas are the non-Hodgkin lymphoma (NHL) (90% of cases) and Hodgkin lymphoma (HL) (10%). Lymphomas, leukemias and myelomas 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, proton 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 89%, while that for non-Hodgkin lymphomas is 74%. 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 in the developing world.
Signs and symptoms
Lymphoma commonly presents with painless, persistent lymphadenopathy (swelling of the lymph nodes) and can vary from rapidly enlarging lymph nodes in aggressive lymphomas to fluctuating lymphadenopathy in slow-growing subtypes. B symptoms are a set of symptoms consisting of fever, night sweats, and unintended weight loss associated with Hodgkin and non-Hodgkin lymphomas. Patients with high histological grade lymphoma are more likely to be affected by these symptoms. The presence of lymphoma outside the lymph nodes can cause a variety of symptoms depending on the affected organ. These symptoms are common in non-Hodgkin lymphoma, with 40% of patients expressing them. Aggressive non-Hodgkin lymphomas make systemic symptoms more likely. Mediastinal lymphadenopathy, and less commonly, pulmonary lymphoma, may cause cough, dyspnea, chest pain, or superior vena cava syndrome, due to compression of the windpipe, the superior vena cava, or nerves in the chest. Lymphoma in bone marrow can cause anemia, thrombocytopenia, and fatigue. This is most common in low-grade, non-Hodgkin lymphomas, and especially in follicular, mantle cell, and small B-cell lymphomas (40-90% of cases depending on subtype). Chronic pain, fullness, early satiety, and gastrointestinal bleeding are symptoms associated with gastrointestinal lymphoma. The gastrointestinal tract is the most common location for extranodal involvement with non-Hodgkin lymphomas, accounting for 30-40% of extranodal lymphomas in general, while in Hodgkin lymphomas, it is rare, accounting for less than 1% of cases. Although uncommon, involvement with the central nervous system can cause symptoms including confusion, double vision, headaches, nausea, and hearing loss. It is rare in Hodgkin lymphomas, with only 0.2% to 0.5% of patients experiencing it, but occurs more often in non-Hodgkin lymphoma, ranging from 2.8% in indolent forms to 24.4% in high-grade lymphoblastic and Burkitt lymphoma. Paraneoplastic syndromes are rare in lymphoma. Paraneoplastic cerebellar degeneration is most strongly associated with Hodgkin lymphomas, while polymyositis and dermatomyositis are associated with both Hodgkin and non-Hodgkin lymphomas.
Diagnosis
Lymphoma is definitively diagnosed by a lymph-node biopsy or biopsy of extranodal tissue, which is examined under the microscope. This examination reveals histopathological features that may indicate lymphoma. Imaging may be performed as part of the initial workup for lymphoma. CT scans can identify enlarged lymph nodes, while fluorodeoxyglucose (FDG) PET imaging identifies areas of increased lymph node activity. Laboratory tests may also be used as part of initial workup to assess affected organ function, blood counts, and conditions that may affect treatment. Complete blood counts can show signs of bone marrow, spleen, and GI tract involvement through blood count abnormalities, including anemia, both low and high platelet count, and low white cell count. Testing for HIV and hepatitis B and C may also be performed due HIV being associated with an increased risk for lymphoma and hepatitis potentially reactivating with certain antibody treatments. After lymphoma is diagnosed, a variety of tests may be carried out to look for specific features characteristic of different types of lymphoma including immunophenotyping (targeting of proteins expressed on cells), flow cytometry, and fluorescence in situ hybridization testing.
Staging
After a diagnosis and before treatment, cancer is staged. This refers to determining if the cancer has spread, and if so, whether locally or to distant sites. Staging is reported using a scale, from I (confined) to IV (spread). The stage of a lymphoma helps predict a patient's prognosis and is used to help select the appropriate therapy. The Lugano classification system, a modified version of the older Ann Arbor staging system (from 1971), is the standard used for staging of both HL and NHL. The specific criteria for each stage are as follows:
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