Lymphoma — Cancer of the Lymphatic System

Lymphoma develops when genetic mutations disrupt the normal cell cycle of T cells, B cells, or natural killer (NK) cells. Instead of protecting against pathogens, these transformed cells divide indefinitely and aggregate within lymph nodes, the spleen, bone marrow, and other extranodal tissues. This continuous accumulation impairs normal haematopoiesis and dampens immune function.

The disease is divided pathologically into Hodgkin lymphoma, marked by the presence of giant multinucleated Reed-Sternberg cells, and non-Hodgkin lymphoma (NHL), which encompasses dozens of biologically unique subtypes. Clinical behaviour spans a wide spectrum, from indolent, slowly progressing forms requiring active monitoring to highly aggressive neoplasms demanding immediate systemic therapy.

Accurate subtyping of lymphoma is critical because treatment plans differ vastly depending on the disease's microscopic and molecular traits. While some indolent lymphomas can be safely observed for long periods without intervention, aggressive subtypes require immediate, intense therapy. Many lymphomas are highly sensitive to modern chemotherapies and targeted immunotherapies. Establishing a precise initial diagnosis and anatomical stage allows the oncology team to formulate treatment regimens that often yield durable remissions.

Definitive diagnosis requires an excisional lymph node biopsy; fine-needle aspiration alone is rarely sufficient. Pathologists utilise immunohistochemistry (IHC) to detect specific cluster of differentiation (CD) markers, such as CD20 or CD30. Molecular and cytogenetic testing, including fluorescence in situ hybridisation (FISH) for translocations like MYC or BCL2, clarifies the subtype. Staging relies on PET-CT scans and occasional bone marrow biopsies.

This term directly encompasses Hodgkin lymphoma and non-Hodgkin lymphoma. Common non-Hodgkin subtypes include diffuse large B-cell lymphoma (DLBCL), follicular lymphoma, mantle cell lymphoma, marginal zone lymphoma, and peripheral T-cell lymphoma. Lymphoma can also present primarily in extranodal organs, such as primary central nervous system lymphoma, cutaneous T-cell lymphoma, or gastrointestinal mucosa-associated lymphoid tissue (MALT) lymphoma.

Therapeutic strategies depend entirely on histology and staging. Standard interventions include chemoimmunotherapy regimens, such as rituximab paired with CHOP for CD20-positive B-cell lymphomas. Targeted therapies, including Bruton tyrosine kinase (BTK) inhibitors, antibody-drug conjugates, and bispecific antibodies, play prominent roles in relapsed disease. Highly refractory cases may benefit from autologous stem cell transplantation or chimeric antigen receptor (CAR) T-cell cellular therapy.