Secondary spleen in immune thrombocytopenia: Not so accessory after all….

Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder characterized by an isolated thrombocytopenia. The pathophysiology is complex but involves platelet-autoantibodies and/or cytotoxic T cells, with the spleen playing an important regulatory role. Accessory spleen (AcS) may possibly contribute to ITP relapse following splenectomy; however, the microenvironment of AcS has not been directly compared to the main spleen. Pizzi et al. conducted a histological study of adult ITP patients where they compared eight matched AcS to main spleens, and they observed a similar immunological composition in both groups. This supports the possibility of AcS-mediated ITP relapse post splenectomy. Commentary on: Pizzi et al. Accessory spleens recapitulate the immune microenvironment of the main spleen in immune thrombocytopenia. Br J Haematol 2023;202:147-152.