Efficacy of tocilizumab monotherapy for autoimmune hemolytic anemia associated with idiopathic multicentric Castleman disease: a case-based review.

Idiopathic multicentric Castleman disease (iMCD) is a rare lymphoproliferative disorder characterized by generalized lymphadenopathy with distinctive histopathological features and systemic inflammation driven by excessive interleukin-6 (IL-6) production. Anemia due to chronic inflammation is a common manifestation of iMCD; however, this disease can also be complicated by autoimmune hemolytic anemia (AIHA). While tocilizumab (TCZ), an IL-6 receptor blockade, has demonstrated efficacy in treating iMCD, its therapeutic effect on AIHA secondary to iMCD remains unclear. Here, we report the first case of iMCD complicated by AIHA successfully treated with TCZ monotherapy, without the need for concurrent glucocorticoid therapy. Notably, AIHA improved along with the disappearance of autoantibodies under TCZ monotherapy, suggesting that IL-6 played a key role in the production of autoantibodies and causing AIHA secondary to iMCD. Furthermore, our literature review identified six other cases of iMCD with AIHA, five of which achieved favorable outcomes with a combination of TCZ and prednisolone, except for one case that developed anti-TCZ antibody. In two cases, AIHA improved without requiring an increase of prednisolone dose. These findings suggest that TCZ may represent a viable therapeutic option not only for iMCD itself but also for AIHA secondary to iMCD.