Immunoglobulin G4-related disease coexisting with rectal cancer: a case report.

So far, at least 12 cases of immunoglobulin G4 related disease (IgG4-RD) coexisting with colorectal cancer have been reported in the literature, but IgG4-RD with rectal cancer is still extremely rare. In addition, recently, the correlation between IgG4-RD and malignancy strongly motivates immunologists and pathologists to conduct further research. In this case study, we present a case of IgG4-RD with rectal cancer and review the pathological characteristics of IgG4-RD and discuss the association between IgG4-RD and malignancy. Indeed, the relationship between IgG4-RD and malignancy is controversial, but we remind physicians that they should be aware of the possible coexistence of malignancy among IgG4-RD patients.