Acute lymphoblastic leukemia in a patient with IgG4-related disease.

IgG4-related disease (IgG4-RD) is a multi-organ immune-mediated condition characterized by tumor-like lesions, fibrosis, and lymphoplasmacytic infiltration to every organ. Recently, an association between IgG4-RD and malignant tumors has been suggested and IgG4-RD is closely related to the occurrence of malignant hematologic diseases. In this report, we describe a rare complication of acute lymphoblastic leukemia in a patient with IgG4-RD. An 81-year-old Chinese man was diagnosed with the lymphadenopathy associated with IgG4-related disease. The histopathological study revealed multiple plasma cells infiltration and immunostaining for IgG and IgG4 was performed on plasma cells and the IgG/IgG4 ratio was more than 40%. Eight months later, he developed acute lymphoblastic leukemia. It has been suggested that the incidence of malignant hematologic diseases may be high in patients with IgG4-RD and increased Th2 cells and Treg cells cytokines may result in the occurrence of hematologic malignancies. Therefore, the importance of accurate diagnosis and intense medical follow-up should be emphasized. Once the patients develop hematologic malignancies, they need to receive treatment timely.