Diseases such as Kikuchi's disease (histiocytic necrotizing lymphadenitis), Kimura's disease (eosinophilic hyperplastic lymphogranuloma), and Rosai-Dorfman disease (sinus histiocytosis with massive lymphadenopathy) may show benign and inflammatory lymphadenopathy in the neck. Kikuchi's disease is a self-limiting and benign lymphadenitis in which cervical nodes are usually affected. Kimura's disease is an autoimmune eosinophilic granulomatous disorder with generalized lymphadenopathy. Rosai-Dorfman disease is a rare idiopathic benign histiocytic proliferation, and massive lymphadenopathy is usually found in the neck region with predominant sinusoidal histiocyte infiltration.
On sonography, lymph nodes involved with Kikuchi's and Kimura's diseases have an appearance similar to that of reactive nodes, which tend to be hypoechoic, and have an echogenic hilus. In patients with Kikuchi's disease, lymph nodes are usually oval (Fig. 12A
), whereas lymph nodes in patients with Kimura's disease are usually round (Fig. 13A
). On power Doppler sonography [12
], lymph nodes in patients with Kikuchi's disease and Kimura's disease tend to show hilar vascularity [12
] (Figs. 12B
). In patients with Rosai-Dorfman disease, involved lymph nodes appear similar to malignant nodes, which are hypoechoic, round, and without echogenic hilus (Fig. 14A
). On power Doppler sonography, involved lymph nodes in Rosai-Dorfman disease also have an appearance similar to that of malignant nodes and show peripheral or mixed vascularity [12
] (Fig. 14B
). Because the sonographic appearance of these unusual lymphadenopathies is similar to that of reactive or malignant nodes, the diagnosis is still based on histology.