[Kikuchi-Fujimoto disease prior to childhood-systemic lupus erythematosus diagnosis].

Kikuchi-Fujimoto disease (KFD) is a self-limiting histiocytic necrotizing lymphadenitis of unknown origin. Of note, KFD was infrequently reported in adult systemic lupus erythematosus (SLE), with rare occurrence in childhood-SLE (C-SLE) patients. To our knowledge, the prevalence of KFD in the paediatric lupus population was not studied. Therefore, in a period of 29 consecutive years, 5,682 patients were followed at our institution and 289 (5%) met the American College of Rheumatology classification criteria for SLE, one had isolated KFD (0.03) and only one had KFD associated to C-SLE diagnoses, which case was reported herein. A 12 year-old female patient had high fever, fatigue and cervical and axillary lymphadenopathy. The antinuclear antibodies (ANA) were negative, with positive IgM and IgG herpes simplex virus type 1 and type 2 serologies. Fluorine-18-fluoro-deoxy-glucose positron emission tomography/computed tomography (PET/CT) imaging demonstrated diffuse lymphadenopathy. The axillary lymph node biopsy showed necrotizing lymphadenitis with histiocytes, without lymphoproliferative disease, compatible with KFD. After 30 days, she presented spontaneous regression and no therapy was required. Nine months later, she developed malar rash, photosensitivity, oral ulcers, lymphopenia and ANA 1:320 (homogeneous nuclear pattern). At that moment the Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score was 10 and she was treated with prednisone (1.0mg/kg/day) and hidroxychloroquine showing progressive improvement of hers signs and symptoms. In conclusion, KFD is a benign and rare disease in our paediatric lupus population. We also would like to reinforce the relevance of autoimmune diseases diagnosis during the follow-up of patients with KFD.