Kikuchi-Fujimoto Disease PET/CT Assessment of a Rare Cause of Cervical Lymphadenopathy

Purpose: Kikuchi-Fujimoto disease (KFD), formerly called subacute necrotizing lymphadenitis, is a rare cause of cervical lymphadenopathy. The purpose of this study was to evaluate the usefulness of FDG PET/CT for distinguishing KFD from non-Hodgkin lymphoma (NHL). Materials and Methods: Twenty-two patients with cervical lymphadenopathy (8 with KFD and 14 with NHL) underwent CT and FDG PET/CT scans to examine the cervical lymphadenopathy. Regional values of FDG uptake were evaluated using the standardized uptake value (SUV) and partial volume corrected SUV ((cor)SUV) based on the count recovery coefficient. Tumor size (mm), SUV, and (cor)SUV were compared among KFD, indolent NHL, and aggressive NHL. Results: KFD lesions tended to be smaller (13.8 +/- 5.4 mm) than those of indolent (25.4 +/- 11.8) and aggressive (29.7 +/- 18.8) NHL, whereas there were no significant differences in size. As for SUV, a significant difference was observed only between indolent and aggressive (6.4 +/- 1.5 and 17.3 +/- 9.3, P < 0.05) NHL; however, KFD showed a significantly greater (cor)SUV (23.8 +/- 10.6) as compared with indolent NHL (9.2 +/- 5.1, P < 0.05), which did not show a significant difference from aggressive NHL (21.4 +/- 10.2). FDG PET/CT detected thoracoabdominal lesions in 2 patients (25%) with KFD. Conclusions: KFD shows high FDG uptake for size, which may reflect the pathologic characteristics, including necrotizing lymphocytes and numerous histiocytes (macrophages) surrounding small necrotic foci. FDG PET/CT will be useful for detecting noncervical lesions of KFD and distinguishing KFD from NHLs using both SUV and (cor)SUV.