Lactate dehydrogenase levels and 18F-FDG PET/CT metrics differentiate between mediastinal Hodgkin's lymphoma and primary mediastinal B-cell lymphoma.

PURPOSE: This study aims to investigate whether clinical, laboratory, and fluorine-18-fluorodeoxyglucose (F-FDG) PET/CT findings can discriminate between mediastinal Hodgkin's lymphoma and primary mediastinal B-cell lymphoma (PMBCL).

PATIENTS AND METHODS: This retrospective study included 56 patients (42 with mediastinal Hodgkin's lymphoma and 14 with PBMCL). Differences in clinical, laboratory, and F-FDG PET/CT metrics were assessed between Hodgkin's lymphoma and PMBCL.

RESULTS: Lactate dehydrogenase (LDH) and F-FDG PET/CT-based maximum tumor diameter, lesion-to-liver ratio maximum standardized uptake value (SUVmax), and lesion-to-liver ratio peak standardized uptake value (SUVpeak) were all significantly higher (P<0.001) in PMBCL than in Hodgkin's lymphoma, and PMBCL also significantly more frequently (P=0.001) exhibited necrosis on F-FDG PET/CT than Hodgkin's lymphoma. LDH, maximum tumor diameter, lesion-to-liver ratio SUVmax, and lesion-to-liver ratio SUVpeak yielded areas under the receiver operating characteristic curve of 0.968 [95% confidence interval (CI): 0.923-1.000], 0.866 (95% CI: 0.765-0.968), 0.875 (95% CI: 0.776-0.975), and 0.874 (95% CI: 0.771-0.976), respectively. LDH (with cutoff of 236 U/l) achieved sensitivity and specificity of 81.6 and 100%, respectively; maximum tumor diameter (with cutoff of 9.98 cm) achieved sensitivity and specificity of 87.2 and 78.3%, respectively; lesion-to-liver ratio SUVmax (with cutoff of 7.12) achieved sensitivity and specificity of 94.9 and 64.3%, respectively; lesion-to-liver ratio SUVpeak (with cutoff of 11.45) achieved sensitivity and specificity of 97.4 and 64.3%, respectively; and the presence of necrosis achieved sensitivity and specificity of 78.6 and 74.4%, respectively, in discriminating PMBCL from Hodgkin's lymphoma.

CONCLUSION: LDH levels and several F-FDG PET/CT findings (tumor size, presence of necrosis, and degree of F-FDG uptake) are helpful in discriminating mediastinal Hodgkin's lymphoma from PMBCL.