MALT Lymphoma (Gastric and Ocular Adnexa and Other Sites)

Steven H. Lin and John P. Plastaras

Background

What does MALT stand for? Where is MALT generally located?

MALT stands for mucosa-associated lymphoid tissue. It is located in the Peyer patches of the bowel and lymphoid tissues of the H&N (nasopharynx [adenoids] or oropharynx [tonsils]), so it is not generally present in the stomach, lung, or salivary glands.

What is the etiology of MALT lymphomas?

The etiology of MALT lymphomas is chronic inflammation from infection or autoimmune disorder.

What are the most common locations of MALT lymphoma in the body?

The most common locations of MALT lymphoma are the GI tract (stomach > small intestine > colon), lung, thyroid, salivary gland, tonsil, breast, and orbit.

What types of infectious or autoimmune conditions are associated with MALT lymphoma in the stomach? Ocular adnexa? Salivary gland? Skin? Thyroid?

Infections or autoimmune conditions associated with MALT:

Stomach: Helicobacter pylori
Ocular adnexa: Chlamydia psittaci
Salivary gland: Sjögren
Skin: Borrelia burgdorferi
Thyroid: Hashimoto thyroiditis

What is the natural Hx of MALT lymphomas?

The natural Hx includes an indolent clinical course, as in low-grade lymphoma.

From where do MALT lymphomas typically arise in the lymphoid follicle?

MALT lymphomas typically arise from the marginal zone of the lymphoid follicle (and therefore are termed as extranodal marginal zone lymphoma).

What are some important cytogenetic abnormalities in MALT lymphomas?

Important cytogenetic abnormalities include t(11;18)(q21:q21) and trisomy 3.

What is the immuno-phenotype of MALT lymphoma?

MALT lymphoma is a low-grade B-cell lymphoma that is CD20 + , CD35 + , CD5 − , and CD10 −.

Workup/Staging

What is the typical stage of MALT lymphomas?

Stage IAE (80%) is typical for MALT lymphomas.

What is the typical presentation of a pt with gastric MALT?

The typical presentation of gastric MALT is dyspepsia (#1), epigastric pain or discomfort, n/v, GI bleed, and B Sx (rare).

What workup should be included in a pt with suspected MALT lymphoma of the stomach?

Suspected MALT lymphoma of the stomach workup: Complete H&P (with emphasis on B Sx and −evaluation of all LNs, including the Waldeyer ring [15% association; check hepatosplenomegaly]), CBC/CMP, LDH, CXR, CT abdomen/pelvis, esophagogastroduodenoscopy (EGD) with Bx, and EUS (to assess DOI). Test for H. pylori infection with a rapid urease test (RUT) on the Bx specimen. Consider BM Bx in pts with suspected systemic Dz.

What is the sensitivity and specificity of the RUT for H. pylori? What are other alternatives if the RUT is negative?

The sensitivity and specificity of RUT is >90%. However, if the test on the tissue sample is negative and the clinical suspicion is high, preferred noninvasive tests are (1) H. pylori serum serology (antibody), (2) urea breath test, or (3) stool antigen test.

How is the Ann Arbor system used for staging MALT lymphoma of the GI tract?

Ann Arbor staging for MALT lymphoma of the GI tract if no B Sx:

Stage IAE: confined to GI tract
Stage IIAE: GI confined + nodal involvement below diaphragm
Stage IIIAE: GI focus + nodes above diaphragm
Stage IVAE: GI + both sides of diaphragm + other extranodal involvement (BM, liver, etc.)