Pseudolymphomatous phase of Kikuchi-Fujimoto disease

Kikuchi-Fujimoto lymphadenitis is a distinctive entity which is easily recognised in its classical histology. However, cases which are biopsied in the early stage of the disease, before entering the necrotic phase may be misdiagnosed as non-Hodgkin's lymphoma. Ten cases of Kikuchi-Fujimoto disease which mimicked non-Hodgkin's lymphoma and in which less than 10% of the lymph node was occupied by necrosis were chosen for this study. The patients included 4 males and 6 females with an age range of 15-40 years. Eight patients presented with cervical lymphadenopathy. The pathologic areas ranged from 70% to 95% of the total nodal area. The features that helped distinguish this lesion from non-Hodgkin's lymphoma were: 1) a sprinkling of karyorrhectic debris throughout the node 2) plasmacytoid monocytes as well as "histiocytes" in the company of transformed lymphocytes (immunoblasts) 3) enlarged mottled T-zone areas, and 4) presence of residual lymphoid follicles. Follow up on six patients revealed no evidence of disease.