FDG-PET scanning for detection and staging of extranodal marginal zone lymphomas of the MALT type: a report of 42 cases.

BACKGROUND: Although reports have suggested that FDG-PET scans were not useful for staging of extranodal marginal zone lymphomas (MZL), experience at our center suggests otherwise. Thus we reviewed the findings of FDG-PET scans in patients with extranodal MZL seen at our center. PATIENTS AND METHODS: A database of 175 patients with histologically-confirmed diagnoses of extranodal MZL was reviewed. Forty-two patients who had had FDG-PET scans for initial staging were identified. All information was obtained by retrospective review of medical records and PET scans. RESULTS: Thirty-four (81%) patients had focal tracer uptake within verified tumor sites, six (14%) patients did not, and two (5%) patients had indeterminate uptake. Seven of the 34 (21%) patients with uptake within verified tumor sites had uptake in regional lymph nodes and four patients were upstaged due to FDG-PET findings. Eight patients also obtained post-treatment FDG-PET scans. In five of those eight, the repeated FDG-PET scan indicated a complete response, and in three there was an indeterminate or mixed response. CONCLUSION: FDG-PET scans carried out for initial staging of extranodal MZL detected disease in a high proportion of patients. This study suggests that imaging with FDG-PET scans is useful for both initial staging and follow-up of patients with extranodal MZL.