Objectives

- Pathophysiology, clinical management and outcomes

- Role of radiology in detection, staging, prognostication and response assessment

- Imaging findings on conventional modalities and nuances in interpretation

- Future directions in radiological assessment (WB-DWI)

Background

Mucosa-associated lymphoid tissue (MALT) lymphoma is a common subtype of non-Hodgkin's lymphoma, frequently involving the stomach.

Chronic Helicobacter pylori infection and genetic factors predispose to development of primary gastric MALT lymphoma. Antibiotic treatment can be effective in H. pylori-positive cases. Chemo-immunotherapy is reserved for patients with progressive, disseminated disease or at high risk of progression e.g. H. pylori-negative, t(11:18) translocation.

A multidisciplinary approach of endoscopic, radiological and histological assessment is the standard of care. However, imaging assessment of the stomach can be challenging with each modality having strengths and limitations.

Imaging findings OR Procedure findings

Images from our specialist radio-oncology database, with histology correlation.

CT findings include protruding, depressed or diffuse patterns. 18F-FDG PET/CT shows high activity co-registering with diseased regions. Both modalities may aid detection of extra-gastric disease.

False-positives include inflammatory gastritis, other gastric malignancies and physiological FDG uptake. Low-grade infiltration can produce a false-negative result. These nuances have implications on accurate staging per Lugano criteria. A Deauville-‘X’ score should be assigned where FDG-avidity is indeterminate for disease.

WB-DWI/ ADC may have a role in staging and response assessment of biopsy-proven disease.

Conclusion

Radiologists play a vital role in informing clinical management of patients with gastric MALT lymphoma.

We hope this review will be a useful reference, especially for colleagues involved in upper gastrointestinal and/or haemato-oncology meetings.