[Kikuchi-Fujimoto disease mimicking malignant lymphoma in adolescents].

Kikuchi-Fujimoto disease, also known as histiocytic necrotizing lymphadenitis, is a rare cause of lymphadenopathy in children. This benign disease can mimic lymphoma and misleads doctors. It was first described in Asia, where it occurred especially in young women. Recent publications show that it can also affect teenagers and young adults in Caucasian populations. The pathophysiology remains unknown. Three hypotheses have been raised for this disease: the role of viruses (in particular HHV-8), genetic predisposition (two alleles in HLA class II genes were found more frequently in patients with Kikuchi disease), and an autoimmune cause because of the correlation with lupus erythematosus. Few cases have been reported in Europe so far. In this article, we report three cases of Kikuchi disease observed in less than 2 months in a single hospital in France. All three patients were teenagers who presented with lymphadenopathy, either isolated or combined with fever, weakness, and weight loss. In all of them, the hypermetabolic activity of the lymph node on the PET scanner misled us to suspect lymphoma. The diagnosis of Kikuchi disease was finally made, for all patients, after 2 weeks in the hospital based on lymph node biopsy. Based on this report, we highlight that early biopsy in presence of lymphadenopathy can avoid unnecessary extensive investigations. Moreover, in this rare disease, it is very surprising to come across three cases that are not family-related, in such a short period of time. This strengthens the hypothesis of the possible implication of an environmental factor in the pathophysiology of Kikuchi disease.