Kimura's disease. Involvement of regional lymph nodes and distinction from angiolymphoid hyperplasia with eosinophilia.

The clinicopathologic features of nine patients with Kimura's disease and 15 patients with angiolymphoid hyperplasia with eosinophilia (ALHE) were studied and compared in order to clarify the confusion between these two entities. The common features shared by both conditions included male predominance, predilection for the head and neck regions, tendency to recur, and vascular nature of the lesion with lymphoid and eosinophilic infiltrates. However, Kimura's disease was usually seen in younger individuals for a longer duration and occurred as a deeply seated, large soft-tissue mass, without significant change of the overlying skin initially. In addition, it was often accompanied by peripheral blood eosinophilia and elevated serum IgE. In contrast, ALHE lesions were multiple small dermal papular or nodular eruptions observed in older patients and present for a shorter duration; they were less frequently accompanied by peripheral blood eosinophilia. The main histopathological difference was the presence of "histiocytoid" or "epithelioid" blood vessels in ALHE but not in Kimura's disease. Kimura's disease was further characterized by eosinophilic folliculolysis; IgE deposits in the germinal centers; and frequent involvement of regional lymph nodes, salivary glands, and skeletal muscles. The eosinophilic infiltration, especially the formation of eosinophilic microabscesses, along with increased number of small blood vessels, perinodal eosinophilic infiltration, and eosinophilic folliculolysis characterized the nodal involvement by Kimura's disease. Our study indicates that Kimura's disease and ALHE are two distinct clinicopathologic entities. We place particular emphasis on the involvement of regional lymph nodes in Kimura's disease. In addition, we observed Charcot-Leyden crystals and polykaryocytes in both conditions. One of the patients with Kimura's disease also had an associated nephrotic syndrome.