Lymphoma in the context of Non-Hodgkin lymphoma

The hepatitis C virus (HCV) is a small (55–65 nm in size), enveloped, positive-sense single-stranded RNA virus of the family Flaviviridae. The hepatitis C virus is the cause of hepatitis C and some cancers such as liver cancer (hepatocellular carcinoma, abbreviated HCC) and lymphomas in humans.

The Epstein–Barr virus (EBV), also known as human herpesvirus 4 (HHV-4), is one of the nine known human herpesvirus types in the herpes family, and is one of the most common viruses in humans. EBV is a double-stranded DNA virus. EBV is the first identified oncogenic virus, a virus that can cause cancer. EBV establishes a permanent infection in human B cells. It uncommonly causes infectious mononucleosis and is also tightly linked to many malignant diseases (cancers and autoimmune diseases). Various vaccine formulations have been tested in humans and other animals; however, none of them were able to prevent EBV infection, thus, no vaccine has been approved to date.

Infectious mononucleosis ("mono" or "glandular fever"), is characterized by extreme fatigue, fever, sore throat, and swollen lymph nodes. EBV is also associated with various non-malignant, premalignant, and malignant EBV-associated lymphoproliferative diseases such as Burkitt lymphoma, hemophagocytic lymphohistiocytosis, and Hodgkin's lymphoma; non-lymphoid malignancies such as gastric cancer and nasopharyngeal carcinoma; and conditions associated with human immunodeficiency virus such as hairy leukoplakia and central nervous system lymphomas. The virus is also associated with the childhood disorders of Alice in Wonderland syndrome and acute cerebellar ataxia and, by some evidence, higher risks of developing certain autoimmune diseases, especially dermatomyositis, systemic lupus erythematosus, rheumatoid arthritis, and Sjögren's syndrome. About 200,000 cancer cases globally per year are thought to be attributable to EBV. In 2022, a large study following 10 million active US military over 20 years suggested EBV as the leading cause of multiple sclerosis (MS), with a recent EBV infection causing a 32-fold increase in MS risk development.

Hematopathology or hemopathology (both also spelled haem-, see spelling differences) is the study of diseases and disorders affecting and found in blood cells, their production, and any organs and tissues involved in hematopoiesis, such as bone marrow, the spleen, and the thymus. Diagnoses and treatment of diseases such as leukemia and lymphoma often deal with hematopathology; techniques and technologies include flow cytometry studies and immunohistochemistry.

In the United States, hematopathology is a board-certified subspecialty by the American Board of Pathology. Board-eligible or board-certified hematopathologists are usually pathology residents (anatomic, clinical, or combined) who have completed hematopathology fellowship training after their pathology residency. The hematopathology fellowship lasts either one or two years. A physician who practices hematopathology is called a hematopathologist.

Hematopoietic stem-cell transplantation (HSCT) is the transplantation of multipotent hematopoietic stem cells, usually derived from bone marrow, peripheral blood, or umbilical cord blood, in order to replicate inside a patient and produce additional normal blood cells. HSCT may be autologous (the patient's own stem cells are used), syngeneic (stem cells from an identical twin), or allogeneic (stem cells from a donor).

It is most often performed for patients with certain cancers of the blood or bone marrow, such as multiple myeloma, leukemia, some types of lymphoma and immune deficiencies. In these cases, the recipient's immune system is usually suppressed with radiation or chemotherapy before the transplantation. Infection and graft-versus-host disease are major complications of allogeneic HSCT.

Leukemia (also spelled leukaemia; pronounced /luːˈkiːmiːə/ loo-KEE-mee-ə) is a group of blood cancers that usually begin in the bone marrow and produce high numbers of abnormal blood cells. These blood cells are not fully developed and are called blasts or leukemia cells. Symptoms may include bleeding and bruising, bone pain, fatigue, fever, and an increased risk of infections. These symptoms occur due to a lack of normal blood cells. Diagnosis is typically made by blood tests or bone marrow biopsy.

The exact cause of leukemia is unknown. A combination of genetic factors and environmental (non-inherited) factors are believed to play a role. Risk factors include smoking, ionizing radiation, petrochemicals (such as benzene), prior chemotherapy, and Down syndrome. People with a family history of leukemia are also at higher risk. There are four main types of leukemia—acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL) and chronic myeloid leukemia (CML)—and a number of less common types. Leukemias and lymphomas both belong to a broader group of tumors that affect the blood, bone marrow, and lymphoid system, known as tumors of the hematopoietic and lymphoid tissues.

An oncovirus or oncogenic virus is a virus that can cause cancer. This term originated from studies of acutely transforming retroviruses in the 1950–60s, when the term oncornaviruses was used to denote their RNA virus origin. With the letters RNA removed, it now refers to any virus with a DNA or RNA genome causing cancer and is synonymous with tumor virus or cancer virus. The vast majority of human and animal viruses do not cause cancer, probably because of longstanding co-evolution between the virus and its host. Oncoviruses have been important not only in epidemiology, but also in investigations of cell cycle control mechanisms such as the retinoblastoma protein.

The World Health Organization's International Agency for Research on Cancer estimated that in 2002, infection caused 17.8% of human cancers, with 11.9% caused by one of seven viruses. A 2020 study of 2,658 samples from 38 different types of cancer found that 16% were associated with a virus. These cancers might be easily prevented through vaccination (e.g., papillomavirus vaccines), diagnosed with simple blood tests, and treated with less-toxic antiviral compounds.

Hodgkin lymphoma (HL) is a cancer where multinucleated Reed–Sternberg cells (RS cells) are present in the lymph nodes. As it affects a subgroup of white blood cells called lymphocytes, it is a lymphoma. The condition was named after the English physician Thomas Hodgkin, who first described it in 1832. Symptoms may include fever, night sweats, and weight loss. Often, non-painful enlarged lymph nodes occur in the neck, under the arm, or in the groin. People affected may feel tired or be itchy.

The two major types of Hodgkin lymphoma are classic Hodgkin lymphoma and nodular lymphocyte-predominant Hodgkin lymphoma. About half of cases of Hodgkin lymphoma are due to Epstein–Barr virus (EBV) and these are generally the classic form. Other risk factors include a family history of the condition and having HIV/AIDS. Diagnosis is conducted by confirming the presence of cancer and identifying Reed–Sternberg cells in lymph node biopsies. The virus-positive cases are classified as a form of the Epstein–Barr virus-associated lymphoproliferative diseases.

Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebrate animal cell. The name "glucocorticoid" is a portmanteau of "glucose", "cortex", and "steroid", referring to its role in regulating the metabolism of glucose, its synthesis in the adrenal cortex, and its steroidal structure.

Glucocorticoids are part of the feedback mechanism in the immune system, which reduces certain aspects of immune function, such as inflammation. They are therefore used in medicine to treat diseases caused by an overactive immune system, such as allergies, asthma, autoimmune diseases, and sepsis. Glucocorticoids have many side effects, including adverse drug reactions. They also interfere with some of the abnormal mechanisms in cancer cells, so they are used in high doses to treat cancer. In particular, they inhibit lymphocyte proliferation, which is significant for lymphomas and leukemias. They can also lessen some side effects of chemotherapy (anticancer drugs).

Hematology (spelled haematology in British English) is the branch of medicine concerned with the study of the cause, prognosis, treatment, and prevention of diseases related to blood. It involves treating diseases that affect the production of blood and its components, such as blood cells, hemoglobin, blood proteins, bone marrow, platelets, blood vessels, spleen, and the mechanism of coagulation. Such diseases might include hemophilia, sickle cell anemia, blood clots (thrombus), other bleeding disorders, and blood cancers such as leukemia, multiple myeloma, and lymphoma. The laboratory analysis of blood is frequently performed by a medical technologist or medical laboratory scientist.