NHLs

Non-Hodgkin lymphomas (NHLs) are a diverse group of lymphoid cancers arising in the lymphatic system, distinct from Hodgkin lymphoma. They can originate from B cells, T cells, or natural killer cells, with B-cell neoplasms representing the majority.

Classification and subtypes: The WHO classification recognizes mature B-cell neoplasms (diffuse large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma) and mature T-/NK-cell neoplasms (anaplastic large cell lymphoma, peripheral T-cell lymphomas, extranodal NK/T-cell lymphoma). They range from indolent to aggressive in behavior.

Clinical features and staging: NHLs commonly present with painless lymphadenopathy, but extranodal involvement can occur in the gastrointestinal tract, skin, or central nervous system. Symptoms may include fever, night sweats, or weight loss. Staging uses the Ann Arbor system, with PET-CT often used for assessment and monitoring.

Diagnosis and prognosis: Diagnosis relies on biopsy with histology, immunophenotyping, flow cytometry, and genetic testing. Prognosis depends on subtype and stage; prognostic indices such as the International Prognostic Index (IPI) are used for several B-cell lymphomas.

Treatment: Management is subtype- and stage-specific. Localized disease may be treated with radiotherapy; systemic disease commonly uses chemotherapy (for example R-CHOP) and rituximab. Options include targeted therapies, immunotherapies, and, in select cases, stem cell transplantation or CAR-T therapy.

Epidemiology and risk factors: NHLs are more common in older adults. Risk factors include immunosuppression (HIV infection, organ transplantation), autoimmune diseases, and infections such as Helicobacter pylori in gastric MALT lymphoma or EBV in other subtypes. No routine screening exists.