OBJECTIVETo investigate the clinicopathologic features, immunophenotypes and differential diagnosis of Kimura's disease (KD) and epithelioid hemangioma (EH).

METHODSNine cases of KD and three cases of EH were evaluated by light microscopy and immunohistochemistry.

RESULTSIn this series, KD occurred predominantly in males, whereas EH had a female predilection. Both KD and EH arose most frequently in the head and neck region. However, KD usually presented as multiple subcutaneous nodules or swellings and was accompanied by lymphadenopathy in some cases. On the other hand, EH appeared only as a small skin nodule or red plaque. Histologically, both lesions may involve the dermis or subcutis. All the 9 KD cases displayed florid hyperplasia of lymphoid tissue, of which, 7 cases exhibited formation of lymphoid follicles and active germinal centers. Proliferation of post-capillary venules were seen between follicles. They were lined by plump or attenuated endothelial cells. Large number of eosinophils aggregated around the vessels or adjacent to the follicles, formation of microabscesses were observed in 3 cases. All the 3 EH cases showed prominent proliferation of vessels (capillary-sized in 2 cases and small to medium-sized in 1 case). The vessels were lined by epithelioid endothelial cells with abundant eosinophilic cytoplasm. The endothelial cells also proliferated within the lumen in 1 case and grew in sheets or cords adjacent to the vessel walls in 2 cases. Some endothelial cells contained intracytoplasmic vacuoles, suggesting formation of primitive vessels. Associated inflammatory component was noted in 2 cases. Lymphoid follicles however were not present and eosinophil infiltration was not as prominent as in KD. Immunohistochemical study in KD revealed B cells in the lymphoid follicles and mostly T cells in the interfollicular regions. In EH, the epithelioid endothelial cells showed strong reactivity to CD31 and factor VIII-related antigen.

CONCLUSIONSKD and EH are two distinctive entities. The former represents a lymphoid hyperplasia and the latter represents a benign vascular tumor. Recognition of the clinical characteristics and morphologic features of KD and EH is very important in making this distinction.