Assessment of tumor burden and treatment response by 18F-fluorodeoxyglucose injection and positron emission tomography in patients with cutaneous T- and B-cell lymphomas.

18F-Fluorodeoxyglucose (FDG)-positron emission tomography (PET) is a unique functional/metabolic imaging modality that is efficacious in nodal staging and detection of extranodal involvement for a variety of lymphomas. We report its novel use in evaluating tumor burden and response to therapy in two patients with cutaneous lymphomas. A 24-year-old woman with aggressive subcutaneous panniculitic T-cell lymphoma associated with fever, arthralgias, lymphadenopathy, mild anemia, and widespread painful lesions refractory to multiple treatment strategies exhibited intense uptake of a glucose analogue at sites of clinically apparent (and clinically imperceptible) disease. Denileukin diftitox therapy resulted in clinical remission, and a repeat PET scan failed to detect residual foci of malignancy. A 38-year-old man with a more indolent multifocal primary cutaneous follicle center B-cell lymphoma characterized by few systemic symptoms and slowly evolving lesions demonstrated only mild glucose analogue uptake at sites of disease. Remission was achieved by radiotherapy and intravenous rituximab, and confirmed by a repeat PET scan. Extracutaneous disease was not evident in either patient by this technique. These preliminary data suggest that FDG-PET may be useful in determining disease activity at the time of initial diagnosis, after treatment, and evaluating a suspected recurrence.