Usefulness of FDG-PET/CT in the diagnosis of acute transformation of Adult T-cell Lymphoma

Objectives Adult T-cell lymphoma (ATL) is a rare type of non-Hodgikin’s lymphoma which often transforms from indolent ATL (chronic, smoldering) to aggressive ATL (acute, lymphomatous) in the following-up course. Although accurate diagnosis of transformation is important for better treatment management, it’s sometimes difficult only by clinical examination and laboratory test in early stage. In this study, FDG-PET/CT was used for the diagnosis of transformation.

Methods A total of 22 (31-72 average 55yo.) patients diagnosed as chronic or smoldering ATL were incorporated in this study. All patients underwent FDG-PET/CT for the check of possible transformation sign in the course of following-up. SUVmax and TLG (total lesion glycolysis) of lesion were measured in lymph node, spleen, and extra-nodal lesion including skin. Final diagnosis was made by subsequent clinical course or biopsy.

Results In total, 17 out of 22 patients developed acute transformation in the final diagnosis. SUVmax and TLG of transformed group was significantly higher (15.3±5.6, 150±45.3) than those of non-transformed group (6.8±2.4, 40±12.3) (p<0.05). Abnormal FDG uptake was seen in 19 out of 22 patients. Abnormal uptakes were seen in skin (n=10), lymph node (n=15), lung (n=3), spleen (n=1) and other extra-nodal site (n=5). Sensitivity, specificity, accuracy of FDG-PET/CT was 84.2%, 66.6% and 81.8% respectively.

Conclusions FDG-PET/CT was useful method to detect early sign of transformation of ATL into aggressive sub-type in the follow-up of indolent ATL.