Abstract
622
Objectives: Following HDT/ASCT, lymphoma patients develop reactive lymphoid hyperplasia more frequently than those receiving conventional chemotherapy. Since Glut1 receptor overexpression is noted in follicular hyperplasia false positive FDG-PET results are expected in this group. Our aim was to correlate FDG-PET/CT findings with histopathology and evaluate PET imaging characteristics after HDT/SCT. Methods: Eighteen lymphoma patients (4 HD, 9 diffuse large cell, 2 T-cell, 3 follicular), (age:54±18) underwent FDG-PET/CT after HDT/ASCT. FDG-PET/CT findings were correlated with biopsy results and 9-month follow up in all. Abnormal FDG distribution was evaluated. Results: The mean interval between HDT/ASCT and FDG-PET/CT was 23±20 months (range:3-66). Biopsies were performed within 1 month of FDG-PET/CT. On histopathology, 15 patients had benign changes (7 follicular hyperplasia, 1 granulomatous, 5 reactive and 2 chronic inflammatory changes), only 3 had recurrence. The SUVmax (mean±SD) in biopsied lymph nodes (LN) was 10.2±4.7. All biopsy sites were in the neck except one (axilla). The original disease sites were congruent with biopsy sites in only 4 patients 2 of whom showed recurrence. In 14 of 15 with reactive changes, multiple hypermetabolic LN’s, mostly in the neck and axilla, were also observed. In 11 of 15 patients with reactive changes, palatine and/or lingual tonsils exhibited intense FDG uptake (SUVmax:8.8±2.2). 14 of 15 patients were relapse free during follow-up, one patient recurred at 7 months at a different site (iliac LN). Conclusions: False positive FDG-PET findings should be expected after HDT/ASCT due to frequent occurence of reactive lymphoid hyperplasia regardless of lymphoma subtype or interval between HDT/ASCT and PET. Reactive hyperplasia usually occurs in the neck/axilla and outside the original disease site. Multiple hypermetabolic LN's and prominent Waldeyer’s ring are frequently observed findings.
- Society of Nuclear Medicine, Inc.