Primary immunodeficiency disease and hematology

Primary immunodeficiency disease (PID) is an inborn error of the immune system, and is characterized by not only susceptibility to infection but also frequent combination with autoimmune diseases and malignancies. PID is principally caused by a germline mutation, and some PID patients develop hematological abnormalities. In some patients, PID is associated with hemophagocytosis-induced cytopenia, neutropenia, thrombocytopenia, and autoimmune cytopenia. In addition, a subset of PID patients presented with myeloid dysplasia. In contrast, hematological and malignant diseases are mainly associated with somatic mutations. However, recent advances in genetic analysis revealed that defects of the same gene might cause PID and hematological disease. Therefore, PID and hematological diseases are not exclusive but rather complementary, and clinicians should remain open to investigating these diseases.