MALT lymphoma

Mucosa-associated lymphoid tissue (MALT) lymphoma is categorized as indolent or low-grade B-cell lymphoma; however, high-grade histologic transformation can occur.

Median age at presentation is approximately 60 years.

The stomach is the most frequently involved organ, and in most cases (90%), there is a strong association between gastric MALT lymphoma and chronic Helicobacter pylori infection.

Other sites that may be involved include the ocular adnexa, lung, parotid gland, skin, intestinal tract, and thyroid. May also occur (rarely) in breasts, dura, and genitourinary tract. Autoimmune diseases have been linked to nongastric MALT lymphoma.

Diagnosis is based on history, physical exam, radiologic imaging studies, histopathologic and immunohistochemical evaluation of the biopsy specimen, and molecular laboratory techniques.

Treatment is based on the histologic subtype and severity of symptoms at presentation. Surgery, radiation therapy, and chemotherapy all play a role. H pylori-eradication therapy is the mainstay of treatment for localized H pylori-positive gastric MALT lymphoma.

MALT lymphomas (also known as extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue) is a mature B-cell neoplasm.[1]Jaffe E S, Harris N L, Stein H, et al. Pathology and genetics of tumours of haematopoietic and lymphoid tissue.​ Lyon: International Agency for Research on Cancer; 2001.[2]Campo E, Jaffe ES, Cook JR, et al. The International Consensus Classification of Mature Lymphoid Neoplasms: a report from the Clinical Advisory Committee. Blood. 2022 Sep 15;140(11):1229-53. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9479027 http://www.ncbi.nlm.nih.gov/pubmed/35653592?tool=bestpractice.com

MALT lymphomas is defined as an "extranodal lymphoma composed of morphologically heterogenous small B cells, including marginal zone cells, cells resembling monocytoid cells, small lymphocytes, and scattered immunoblasts and centroblast-like cells".[3]Jaffe ES, Harris NL, Stein H, et al, eds. World Health Organization classification of tumors. Pathology and genetics: tumors of haemopoietic and lymphoid tissues. Lyon, France: IARC Press; 2008.​ Plasma cell differentiation occurs in a proportion of cases. The infiltrate is located in the marginal zone of reactive B-cell follicles and extends into the interfollicular region. Lymphoepithelial lesions develop in epithelial tissues due to infiltration of the epithelium with neoplastic cells.[3]Jaffe ES, Harris NL, Stein H, et al, eds. World Health Organization classification of tumors. Pathology and genetics: tumors of haemopoietic and lymphoid tissues. Lyon, France: IARC Press; 2008.