Ultrasonographic differentiation between Kikuchi's disease and lymphoma in patients with cervical lymphadenopathy

Purpose: Kikuchi's disease, or histiocytic necrotizing lymphadenitis, is a self-limited necrotizing lymphadenitis. Clinically, it resembles lymphoma. We want to compare the sonographic features between Kikuchi's disease and lymphoma in patients with cervical lymphadenopathy. Materials and methods: The study protocol was approved by the institutional review board. Two hundred and twenty six cervical lymph nodes (137 nodes from 21 Kikuchi's disease patients and 89 nodes from 20 malignant lymphoma patients) were examined. The demographic and ultrasonographic characteristics of lymph nodes were collected and analyzed. Results: The Kikuchi's disease patients (mean age, 24.2 years; range, 8–57 years) were younger than those with lymphoma (mean age, 54 years; range, 13–81 years). There was no difference in laterality of nodes (p = 0.19). The nodal distribution demonstrated most enlarged neck lymph nodes located at level II, III and V. The ranges of short-axis and long-axis length were 6.5 ± 2.3 mm (mean ± SD) versus 13.4 ± 5.1 mm and 13.4 ± 5.0 mm versus 21.2 ± 9.2 mm for Kikuchi's disease versus lymphoma (p < 0.01), respectively. The S/R ratio of Kikuchi's disease nodes was 0.5 ± 0.2 compared to 0.7 ± 0.2 in lymphoma nodes (p < 0.01). Eighty-seven of 137 nodes (63.5%) of Kikuchi's disease, and eight of 89 nodes (9%) of malignant lymphoma had signs of cortical widening (p < 0.01). Seventy-six nodes (55.5%) of Kikuchi's disease and twenty-eight nodes (31.5%) of malignant lymphoma were matted (p < 0.01). Forty-five of 89 nodes among lymphoma and twenty-four among 137 of Kikuchi's disease had features of micronodular reticular echotexture (p < 0.01). All nodes exhibited hypoechogenicity except one lymphomatous node demonstrated isoechogenicity, and there was no difference in sharpness of border and presence of echogenic hilum between the two diseases (p > 0.05). Conclusion: Analysis of basic ultrasonographic characteristics (size, shape, rims, matting and echotexture) helps differentiate cervical lymph nodes in patients with Kikuchi's disease and lymphoma. Cervical lymphadenopathies in patients with Kikuchi's disease have smaller size, less round, less micronodular reticular echotexture, and more signs of matting and cortical widening than those with lymphoma examined under ultrasound.