Role of 18F-FDG PET/CT in the management of patients with primary breast lymphoma.

Objectives Primary breast lymphoma (PBL) is uncommon but distinct clinic-pathological entity. It accounts for only 0.04 0.5% of all breast malignancies, 0.38 0.7% of all non Hodgkin's lymphomas (NHLs) and 1.7 2.2% of extranodal NHLs. Not much literature available on role of 18F-FDG PET/CT in PBL. To the best of our knowledge, this is the largest study evaluating the role of 18F-FDG PET/CT in the management of primary breast lymphoma.

Methods Thirteen female patients with median age of 32 years (range: 27- 64) who were found to have PBL underwent 31 18F- PET/CT scans for various indications. Out of these 13 patients, 5 patients underwent 18F-FDG PET/CT once, 2 patients twice, 3 patients thrice, 2 patients four times and 1 patient underwent this study five times. 18F-FDG PET/CT image interpretation and analysis was performed qualitatively (visually) and semi-quantitatively using standardized uptake value (SUV) by two nuclear medicine physician. Final diagnosis was made based on correlation with clinical, biopsy, follow up and other imaging modality

Results 18F-FDG PET/CT scan was done for different indications in these patients with PBL. 18F-FDG PET/CT was used for primary staging in 5 patients, for treatment response evaluation in 12 patients and for evaluation of recurrent disease in 14 patients. Five patients were correctly staged with the help of 18F-FDG PET/CT. All the 12 patients evaluated for treatment response showed complete response to treatment post chemotherapy/radiotherapy (RT). Six of them had no prechemotherapy 18F-FDG PET/CT scan but there was resolution of pre-chemotherapy lesions seen on other imaging modalities like computed tomography (CT) or mammography. 18F-FDG PET/CT revealed recurrent/residual disease post lumpectomy in one of the patients evaluated for restaging of disease. In rest of the 6 patients with suspected recurrence/residual disease either clinically or on CT scan, 18F-FDG PET/CT ruled out any evidence of disease. Six out of 13 patients, who had negative post treatment 18F-FDG PET/CT scan, also had a negative 18F-FDG PET/CT scans in follow-up reassuring the high negative predictive value (NPV).

Conclusions 18F-FDG PET/CT has definitive role in the management of patients with rare primary breast lymphoma. It can help in accurate staging of these patients, assessing chemotherapy/RT response and can rule out the evidence of disease in restaging of patients with very high negative predictive value.