Image of the Month—Diagnosis

Extranodal marginal zone B-cell lymphomas of MALT type, commonly termed MALT lymphomas, are the cause of 10% to 15% of all cases of non-Hodgkin lymphoma, and the gastrointestinal tract is the most common site of extranodal non-Hodgkin lymphoma. The majority of MALT lymphomas are of gastric origin. Nongastric MALT lymphomas are most commonly found in the head, neck, and ocular adnexa with only 8% of nongastric MALT lymphomas occurring in the intestinal tract.¹ Although the association of Helicobacter pylori with MALT lymphoma has been clearly defined in the stomach, the role of infectious agents in the etiology of nongastric MALT lymphomas has not yet been determined.

The use of surgical treatment for gastric MALT lymphoma has been declining as antibiotics directed at H pylori effect remission in nearly all patients with low-grade lesions. The optimal treatment of nongastric MALT lymphomas has not been fully elucidated. For low-grade localized lesions, surgical resection is considered curative while high-grade lesions are often treated by surgical resection, CHOP chemotherapy (cyclophosphamide, vincristine, doxorubicin, prednisolone), and/or radiotherapy. However, the benefit of antibiotic therapy for intestinal MALT lymphoma remains unclear. Of all primary small- and large-intestinal non-Hodgkin lymphomas, MALT lymphomas have the best prognosis with a 5-year survival rate of 93% for all risk groups and a 99% 5-year survival for the International Prognostic Index low-risk group.²

Most patients with malignant lymphoma of the gastrointestinal tract present with nonspecific symptoms: vomiting, abdominal fullness, and abdominal discomfort. Endoscopically, intestinal MALT lymphomas are typically sessile, pedunculated lesions with normal-appearing mucosa,³ as was seen in our patient. Diagnosis is made by histologic analysis and demonstration of marginal zone B-cell immunophenotype. In our patient, the decision to perform an en bloc resection of an unknown mass was based on the high likelihood of malignancy as the lead point of the intussusception. Neoplastic lesions as the lead point of an intussusception are associated with certain characteristics: greater length and diameter of obstructed bowel, increased rates of bowel obstruction, and a higher incidence of intussusceptions involving the colon. Malignant lead points occur more frequently in ileocolic and colocolic lesions (approximately 50% to 60%) than intussusceptions of the small intestine (approximately 1% to 40%).⁴

Correspondence: Casey Jo Humbyrd, Department of Medical Education, One Gustave Levy Place, New York, NY 10029 (casey.humbyrd@mssm.edu).

Accepted for Publication: February 25, 2006.

Author Contributions:Study concept and design: Humbyrd, Lin, Baril, and Kim. Acquisition of data: Humbyrd and Lin. Analysis and interpretation of data: Humbyrd. Drafting of the manuscript: Humbyrd and Baril. Critical revision of the manuscript for important intellectual content: Humbyrd, Lin, Baril, and Kim. Administrative, technical, and material support: Humbyrd. Study supervision: Lin, Baril, and Kim.

Financial Disclosure: None reported.