lymphoma

lymphoma
Field	Oncology, Hematology

lymphoma. It is a group of blood cancers that develop from lymphocytes, a type of white blood cell integral to the immune system. The disease typically originates in lymph nodes or other lymphatic tissue, leading to the formation of solid tumors. Major categories include Hodgkin lymphoma and the more common Non-Hodgkin lymphoma, each with numerous distinct subtypes requiring different clinical approaches.

Classification

The modern classification of these malignancies is primarily based on the World Health Organization system, which integrates histological, immunophenotypic, genetic, and clinical features. The fundamental division is between Hodgkin lymphoma, characterized by the presence of Reed–Sternberg cells, and Non-Hodgkin lymphoma, which encompasses all other types. Within Non-Hodgkin lymphoma, major subtypes include indolent forms like follicular lymphoma and aggressive forms such as diffuse large B-cell lymphoma. Other important entities include mantle cell lymphoma, Burkitt lymphoma, and primary mediastinal large B-cell lymphoma. The Lugano classification is commonly used for staging these diseases, assessing the extent of spread from a single lymph node region to involvement of organs like the bone marrow or liver.

Signs and symptoms

The most common presenting sign is painless swelling of lymph nodes in the neck, armpit, or groin, known as lymphadenopathy. Systemic symptoms, often termed "B symptoms," include unexplained fever, drenching night sweats, and significant weight loss. Patients may experience persistent fatigue, pruritus, or pain at sites of disease following alcohol consumption. Involvement of organs outside the lymphatic system can cause a wide array of symptoms; for instance, disease in the mediastinum may lead to cough or superior vena cava syndrome, while infiltration of the gastrointestinal tract can cause abdominal pain or obstruction.

Causes and risk factors

While the exact cause remains unclear in most cases, several infections, immune deficiencies, and environmental exposures are established risk factors. The Epstein–Barr virus is strongly associated with Burkitt lymphoma, Hodgkin lymphoma, and lymphomas arising in immunocompromised patients. Other infectious agents linked to specific subtypes include Human T-lymphotropic virus 1, Hepatitis C virus, and Helicobacter pylori. Conditions that suppress the immune system, such as HIV/AIDS, post-organ transplant states, and autoimmune diseases like Sjögren's syndrome, elevate risk. Exposure to certain chemicals, including herbicides and insecticides, and previous treatment with chemotherapy or radiation therapy for other cancers are also recognized risk factors.

Diagnosis

Diagnosis requires a biopsy of an affected lymph node or tissue, examined by a pathologist using histology and immunohistochemistry. Key tests to identify cell lineage and subtype include flow cytometry to detect specific CD markers and genetic studies such as fluorescence in situ hybridization to identify translocations like t(14;18) in follicular lymphoma. Staging workup involves imaging with positron emission tomography combined with computed tomography, and a bone marrow biopsy to assess dissemination. Blood tests, including a complete blood count and measurement of lactate dehydrogenase, provide additional prognostic information.

Treatment

Treatment strategies vary dramatically by subtype, stage, and patient factors. For many aggressive lymphomas, first-line therapy often involves multi-agent chemotherapy regimens such as R-CHOP, which combines the monoclonal antibody rituximab with cyclophosphamide, doxorubicin, vincristine, and prednisone. Radiation therapy may be used for localized disease. For Hodgkin lymphoma, protocols like ABVD or BEACOPP are standard. Stem cell transplantation, either autologous or allogeneic, is considered for relapsed or refractory disease. Novel agents include ibrutinib, chimeric antigen receptor T-cell therapy approved by the U.S. Food and Drug Administration, and bispecific T-cell engagers like blinatumomab.

Prognosis

Prognosis is highly heterogeneous, depending on the specific subtype, stage at diagnosis, and the patient's age and overall health. International prognostic indices, such as the International Prognostic Index for Non-Hodgkin lymphoma and the International Prognostic Score for Hodgkin lymphoma, integrate factors like lactate dehydrogenase level and disease stage to estimate outcomes. While aggressive lymphomas can be rapidly fatal without treatment, many are curable with modern therapy. Indolent lymphomas are often manageable as chronic diseases for many years, though they are typically incurable with standard approaches. Long-term follow-up is essential to monitor for potential late effects of treatment, including secondary malignancies and cardiovascular disease.

Category:American Society of Hematology Category:National Cancer Institute