Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by the production of multiple autoantibodies and multi-organ involvement. The detection of autoantibodies plays a pivotal role in the diagnosis and differential diagnosis of SLE. We report a case of a male patient whose clinical presentation and immunological profile are extremely similar to those of SLE, accompanied by multiple positive autoantibodies. However, comprehensive evaluation, including multi-site biopsies, led to a definitive diagnosis of Castleman disease (CD). This case highlights the striking clinical and serological overlap between autoantibody-positive CD and SLE. We discuss the distinguishing features of CD and SLE, as well as potential immune mechanisms underlying autoantibody production in CD. Our findings underscore the importance of considering CD in the differential diagnosis of SLE-like syndromes and suggest that future classification systems for SLE may benefit from incorporating underlying biological pathways rather than relying solely on clinical and serological criteria.

We reported a case of CD with multiple positive autoantibodies and multiple organ involvement through case description. The patient was eventually diagnosed through renal biopsy, skin biopsy and lymph node biopsy. By comparing and analyzing the patient's symptoms with typical SLE manifestations, we identified the main clinical and pathological manifestations, pathogenesis and pathological process of these two diseases.

Through our report study on these patients, we would like to remind all clinicians that during the diagnosis of SLE, they need to be vigilant in identifying rare hematological disorders. This case also reminds us that the same clinical manifestations may be based on different disease pathological processes, and careful differentiation is necessary.

Our findings underscore the importance of considering CD in the differential diagnosis of SLE-like syndromes and suggest that future classification systems for SLE may benefit from incorporating underlying biological pathways rather than relying solely on clinical and serological criteria. At the same time, it also reminds us of the limitations of the current classification criteria for lupus erythematosus. The new classification criteria based on the pathological process of the disease have become the next issue that needs to be considered in the diagnosis and treatment of erythema lupus.