18F-fluorodeoxyglucose-positron emission tomography in evaluation of primary cutaneous lymphoma.

Background: The diagnosis of primary cutaneous lymphoma (PCL) is currently based on clinical and histological findings and/or relatively invasive procedures such as bone marrow and fine-needle lymph node biopsies. Although computed tomography (CT) is a noninvasive imaging modality that is widely used for staging in patients with lymphoma, it cannot provide information about malignant cutaneous lesions.
Objectives: To investigate the usefulness of (18)F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) in the management of PCL.
Methods: We retrospectively analysed 31 FDG-PET studies in 19 patients with PCL [15 T-cell non-Hodgkin lymphoma (NHL) and four B-cell NHL]. There were 10 men and nine women (age range 23-84 years, mean +/- SD 54 +/- 16). Eleven FDG-PET studies were performed for initial staging and 20 FDG-PET studies were performed for restaging following therapy. Results of FDG-PET were compared with those of CT. Clinical parameters and/or biopsy results of lesions served as reference for the accuracy of PET and CT in evaluating local and metastatic lesions.
Results: For the initial staging, FDG-PET had a sensitivity of 82% for the evaluation of local disease and 80% for the detection of distant metastasis. The corresponding values for CT were 55% and 100%, respectively. For restaging of cutaneous lymphoma, FDG-PET had a sensitivity of 86% and specificity of 92% for local recurrence/residual disease and a sensitivity of 100% and specificity of 100% for distant metastasis. The corresponding values for CT were 50% and 83% for local recurrence/residual disease and 100% and 67% for distant metastasis.
Conclusions: FDG-PET has a potential value for initial staging and restaging following therapy in patients with PCL. FDG-PET has higher diagnostic value than CT in the detection both of local disease and distant metastasis.