Kikuchi-Fujimoto lymphadenitis.

Kikuchi-Fujimoto disease (KFD), also known as histiocytic necrotizing lymphadenitis, was initially described as a distinct histologic pattern of lymphadenitis generally associated with a benign self-limited clinical course. While most common in Southeast Asia, where KFD was initially described in 1972 in young women, this lesion has since been reported in patients of virtually any age, gender, or ethnic background from a variety of geographic locations, including the United States. In addition, cases showing extranodal involvement have been described. The spectrum of clinical and histologic features associated with this disorder suggest that KFD more likely represents a common pattern of response to a variety of etiologic factors rather than a single clinicopathologic entity. In this review, the characteristic clinical, laboratory, histologic, and immunophenotypic features of this disorder are described, with emphasis on differential diagnosis with other types of necrotizing lymphadenitis and with malignant lymphoma. Unusual clinical presentations and features of disease when present at extranodal sites are also reviewed.