Why is Kikuchi–Fujimoto disease misleading?

Background Kikuchi-Fujimoto disease (KFD) or histiocytic necrotizing lymphadenitis is a rare, benign, autoimmune condition characterized by lymphadenopathy, fever, and neutropenia. KFD has also been frequently reported in association with systemic lupus erythematosus (SLE). Report We report a case of skin manifestations in KFD characterized by malar rash, photosensitivity, panniculitic lesions, positive antinuclear antibodies and nDNA, and negative extractable nuclear antigen. A biopsy performed on deep nodules on the arms revealed an infiltrate of monocytic cells. Electron microscopy showed no lymphocytic infiltrate at or below the basal membrane and no necrotic keratinocytes within the basal cells of the epidermis. Conclusion Histological and ultrastructural data showed that skin manifestations of KFD and SLE share some common features. Electron microscopy analysis can help discriminate between the two diagnoses. © 2011 The International Society of Dermatology.