spontaneous regression of follicular, mantle cell, and diffuse large B-cell non-Hodgkin's lymphomas detected by FDG-PET imaging

Abstract

Spontaneous regression of non-Hodgkin lymphoma (NHL) has been reported in low-grade tumors but is an extremely rare event in intermediate- and high-grade disease. Documentation of spontaneous regression by serial fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging has not been reported in the literature. We present 3 cases of spontaneous regression, 1 each of follicular lymphoma (FL), mantle cell lymphoma (MCL), and diffuse large B-cell lymphoma (DLBCL), which showed spontaneous regression on serial FDG-PET imaging. All patients underwent serial whole-body FDG-PET scans 60 minutes after intravenous injection of 9-11 mCi of this radiotracer. None of them had any chemotherapy, radiotherapy, or surgery after the baseline PET scan. Spontaneous regression of disease in all 3 cases was correlated with conventional imaging and clinical course. All 3 patients had positive FDG-PET results on their baseline scan. There was complete disappearance of FDG uptake on a follow-up PET scan for the patient with follicular lymphoma. These results suggest complete regression. The patients with MCL and DLBCL both showed a significant reduction in FDG uptake on serial whole-body PET scans, suggesting partial regression in both cases. Although spontaneous regression of lymphoma is uncommon, this phenomenon can be successfully demonstrated by FDG-PET imaging. Therefore, serial PET imaging may play an important role in detecting this unusual event and may further enhance our understanding of the biologic behavior of this malignancy.

Case Details

Disease Location

Left axillary lymph nodes

Personal Characteristics

45 -year-old male was diagnosed with diffuse large b-cell lymphoma in 1998, was treated with radiation and chemo in 1998-1999 and remained in complete remission until dec 2002

Clinical Characteristics

In dec 2002, a chest CT revealed disease in the left axillary lymph nodes. An fdg-PET on week after the CT and confirm the CT findings. The PET revealed at least 6 abnormal foci of intense uptake of varying size and intensity in the left axillary region, suggesting active disease. Two other sites of fdg uptake were noted, the right mediastinum and the para-aortic region, also suggesting involvement by the disease left axillary ln excisional biopsy occured and results were consistent with active dlbcl follow-up PET in april 2003 revealed 4 foci of increased uptake in the left axilla that appeared to be less intense than the previous study, the right mediastinum and the para-aortic regions were still present but appeared less intense than the initial scan no treatment was initiated although a follow-up CT in 2003 showed no abnormalities, the PET in june 2003 revealed mild to moderately increased uptake in the left axilla but was still less than the previous scan, suv was not calculated findings were interpreted to represent inflammatory changes but the possibility of residual tumor count not be excluded

Remission Characteristics

Follow-up PET in april 2003 revealed 4 foci of increased uptake in the left axilla that appeared to be less intense than the previous study, the mediastinum and the para-aortic also appeared less intense follow-up CT in june 2003 revealed no abnormalities, and the PET still revealed uptake but less than the previous scan third PET scan noted less intense uptake for left axilla region, but no longer could visualize the mediastinum and para-aortic regions

Treatment & Mechanisms

Proposed Remission Mechanisms

Modulation of the host immune system, possibly by concurrent bacterial or viral infection or traumatic effects including reduction of tumor burden by biopsy immunomodulatory effect

Clinical Treatment

Excisional biopsy

Non-Clinical Treatment

None reported