FDG PET in the Staging and Management of Cutaneous T Cell Lymphoma

We aimed to assess the usefulness of 18F-FDG PET in siting lymphoma involvement for CTCL patients. We retrospectively analyzed CTCL patients who had received a lymph node biopsy within approximately one month of a PET scan. Between 2003 and 2007, 19 CTCL patients (7 males, 12 females, age range: 4 – 70, median: 55) underwent a combined 56 PET scans. All studies were performed on GE Discovery LS 8 slice MDCT PET CT scanner or GE Discovery DST 16 slice MDCT PET CT scanner (Milwaukee, WI) and the images were interpreted on a GE AW or Xeleris workstation. The patients underwent whole body imaging from the head to foot at 4 minutes per bed position. Of these 19 patients, eight patients (four men, four women, mean age: 56.6, range: 49 – 70) received a lymph node biopsy following a PET scan that demonstrated elevated focal uptake (SUVs ranging from 2.2 to 9.9) in at least one lymph node. In four of the cases, the biopsied lymph node directly confirmed CTCL involvement sited in that node by PET scan (SUV 2.2 to 6.1). Three cases represented false-positive PET scans which were attributed to category 1 dermatopic lymphadenopathy and post radiation change. Despite these lack in correlations, in one case, PET sited adenopathy (SUV 9.9) in an inguinal node that biopsy pronounced benign. Further studies proved that a sampling error produced a false-negative biopsy. Despite the small sample, the study demonstrates the importance of PET imaging in staging patients with CTCL. Findings suggest that lymph node SUV values ranging from 2.2 – 9.9 often correlate with definite involvement of the nodes, and consequentially progression of the disease. It was found that false-positive PET scans may result from post radiation change or dermatopathic lymphadenopathy, category 1. The sample size was too small to detect differences in SUV and correlation in lymph node involvement. Our study demonstrates the need for improvement in the specificity of FDG-PET scans possibly by two point imaging and accurate localization of lymph nodes by use of an intraoperative probe to further enhance its usefulness in the staging of CTCL. Further prospective study is needed to determine correlation with SUV and lymph node involvement.