Originally described in the 1980s,
mucosa-associated lymphoid tissue (MALT) lymphoma is an indolent,
B-cell lymphoma that has been reclassified by the revised
European-American Lymphoma (REAL) classification system as
extranodal, marginal zone B-cell lymphoma. In the majority of stage
IE patients, the causative agent is Helicobacter pylori, and
treatment with antibiotics often resolves the lymphoma (Roggero E et
al: Ann Intern Med 122:767-769, 1995). If antibiotic therapy
fails, the next step would be chemotherapy, radiation, or surgery.
However, certain patients are not candidates for these modalities.
We retrospectively reviewed five cases of gastrointestinal (GI) MALT
lymphomas from 1996 to 1999. The five patients had all been treated
with the anti-CD20 monoclonal antibody, rituximab (Rituxan), after
not responding to antibiotics directed against H pylori; none
of the patients was a surgical candidate. Rituximab is approved for
CD20-positive follicular lymphomas. MALT lymphomas are B-cell and
CD20-positive or L-26positive; immunohistochemical stain for CD 0).
Rituximab was administered at 375 mg/m² weekly for 4 weeks.
Median age of the patients was 59 years (range, 24 to 81 years), with
three males and two females. Four patients had stage IE disease and
one, stage IIE. All patients were diagnosed by endoscopy, with
pathology showing positivity of L-26 stain on the lymphoepithelial
lesions of the biopsy specimens.
Primary sites of disease were the rectum (N = 1), stomach (N = 3),
and cecum (N = 1). The patient with stage IIE MALT had disease in the
stomach and jejunum.
Only one patient was positive for H pylori, seen morphologically on
the biopsy and by the urease test on the specimens. Three patients
had associated inflammatory disorders: chronic gastritis (N = 2) and
primary sclerosing cholangitis (N = 1).
Initial post-rituximab endoscopy was performed at 3 months and then
every 6 months thereafter. All patients underwent pretreatment CT of
the chest, abdomen, and pelvis, as well as bone marrow biopsy, and
two patients had gallium scans.
The response rate was 100% (four complete responses [CRs] and one
partial response [PR] > 50%). All patients are alive with a median
follow-up of +19 months (range, 12 to 38 months). At present, three
patients are still in CR, with a median response duration of 13
months, one patient has residual disease, and one patient relapsed 11
months after treatment. Toxicity was minimal, consisting mainly of
infusion-related effects (fever, chills, and myalgia).
CONCLUSION: Patients with MALT lymphomas of the GI tract respond very
well to rituximab with minimal toxicity. Longer follow-up is needed
to assess the long-term disease-free survival in this group of
patients with an indolent lymphoma. A larger cohort of patients
should be studied utilizing a combined-modality approach. Rituximab
is another therapeutic approach to MALT lymphomas that can be used in
patients who do not respond to H pylori antibiotics and are
not surgical candidate