Cerebral hemorrhage from an incidental cavernous malformation occurring at the progressive stage of immunoglobulin G4-related disease

The effect of IgG4-RD on CCM remains unknown. The simultaneous worsening of IgG4-RD and hemorrhage from CCM in our case strongly suggests an association between IgG4-RD and CCM, and we consider cytokines to be the key factors in this association. Theoretically, increased levels of certain serum cytokines, such as IL-5, in patients with IgG4-RD could affect CCM. Underlying disorders should be considered when a progressive and aggressive CCM is detected.