Marginal zone lymphoma (MZL) is an indolent mature B-cell lymphoma arising from the marginal zone of lymphoid tissues. It comprises three distinct entities: extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma, most commonly affecting the stomach, lung, skin, and ocular adnexa); nodal marginal zone B-cell lymphoma (affecting lymph nodes without extranodal involvement); and splenic marginal zone lymphoma (involving the spleen, splenic hilar lymph nodes, bone marrow, and often peripheral blood). The condition affects approximately 1 to 9 per 100,000 individuals.

Marginal zone lymphoma is characterized histologically by the presence of small to medium-sized atypical lymphocytes. Clinical manifestations vary by anatomic subtype and affected site, and may include lymph node enlargement, splenomegaly, and organ-specific signs arising from extranodal disease involvement. Specific phenotypic data are not certified in this packet.

The genetic basis of marginal zone lymphoma is not established in this data packet. As an acquired B-cell malignancy, MZL arises from mature B-lymphocytes of the lymphoid marginal zone through somatic processes rather than germline inheritance. No Mendelian inheritance pattern applies to this condition.

Diagnosis of MZL requires histopathologic examination demonstrating characteristic small to medium-sized atypical B-lymphocytes, with classification by anatomic site of origin. Diagnostic criteria differ across the three recognized subtypes — MALT, nodal, and splenic. Specific diagnostic methods beyond histopathologic classification are not detailed in this packet.

No therapies appear in the approved treatments field for marginal zone lymphoma in this data packet. Treatment planning depends on disease stage, subtype, and overall health status. Management typically involves a multidisciplinary oncology team and may encompass site-directed local therapies, systemic treatment approaches, and supportive care. Treatment goals — whether focused on disease control or curative intent — are individualized based on the specific clinical presentation and subtype.

Prognosis for MZL is not individually certified in this data packet. As described in the disease definition, the condition typically follows an indolent clinical course. Specific outcomes depend on subtype, disease stage, and response to treatment; no survival or progression data are provided in this packet.

Numerous active clinical trials are investigating marginal zone lymphoma. Notable documented examples include NCT05006716 (Phase I), examining a novel investigational compound in B-cell malignancies (BeOne Medicines, recruiting), and NCT05100862 (Phase III), evaluating a combination immunotherapy regimen in relapsed or refractory follicular lymphoma or MZL (BeOne Medicines). A longitudinal hematology registry study (NCT06043011) is also actively enrolling participants. Active clinical trials for this condition are listed on ClinicalTrials.gov.