MALT Lymphoma Flashcards
What does MALT stand for? Where is MALT generally located?
MALT stands for mucosa-associated lymphoid tissue. It consists of small concentrations of lymphoid tissue found in the mucosa of various sites of the
body, such as the GI tract.
What is the etiology of MALT lymphomas?
Chronic inflammation from infection or autoimmune disorder predisposes to the development of MALT lymphomas.
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 syndrome, hepatitis C
Skin: Borrelia burgdorferi
Thyroid: Hashimoto thyroiditis
What is the natural Hx of MALT lymphoma?
The natural Hx follows an indolent clinical course, as a low-grade lymphoma. MALT lymphomas typically remain localized to the tissue of origin.
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 also 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 immunophenotype of MALT lymphoma?
MALT lymphoma is a low-grade B-cell lymphoma that is CD20+, CD35+, CD5–, and CD10–.
What is the typical stage of MALT lymphomas?
Because MALT lymphomas remained localized to a particular tissue, most are usually Ann Arbor stage IAE (80%).
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 if available (to assess DOI). Test for H. pylori infection with a rapid urease test (RUT) on the Bx specimen and test for t(11;18) with FISH or PCR. Consider
BM Bx in pts with suspected systemic Dz. Routine PET/CT is not considered necessary but may be useful in some cases.
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 are >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 + nodal involvement below diaphragm
Stage IIIAE: GI + nodes above diaphragm +/– nodes below diaphragm
Stage IVAE: GI + other extranodal involvement (BM, liver, etc.) +/– nodes above or below diaphragm
What is the 1st-line therapy used for the Tx of gastric MALT lymphoma?
If there is documented H. pylori infection, the initial therapy is H. pylori eradication (triple therapy of clarithromycin/metronidazole/proton pump inhibitor (PPI) or clarithromycin/amoxicillin/PPI). If there is lymphoma but
the pt is H. pylori–, consider RT as a primary therapeutic approach,especially if there are chromosomal abnormalities.
How is the eradication of H. pylori determined?
A urea breath test should be done 1 mo after antibiotic use. If there is persistence of tumor and H. pylori infection, switch to a different antibiotic regimen.
What response rate is expected from 1st-line Tx of gastric MALT lymphoma?
75%–80% of pts have a CR (Wündisch T et al., JCO 2005), with an extremely low rate of relapse.
What is the typical response period to antibiotics in MALT lymphoma?
In MALT lymphoma, regression can be slow. In 1 study of 120 pts, the 1st CR after antibiotic therapy was diagnosed between 1 mo and 28 mos after the
start of the H. pylori eradication Tx. The majority of pts (61%) achieved a CR within the 1st 3 mos after Tx. However, in some pts, it took up to 28 mos for
all histologic evidence of lymphoma to resolve. (Wundisch T et al., JCO 2005)