Castleman's disease is a rare atypical lymphoproliferative disorder. Although HHV-8 has been reported to be a cause of Castleman's disease, the etiology and pathogenesis of the disease remains mostly unknown. We experienced a 51-year-old female patient who was concurrently diagnosed with Castleman's disease and systemic lupus erythematosus. Castleman's disease has been rarely reported in patients with systemic lupus erythematosus. Thus, we report the case and briefly discuss relevant articles.