hematology and oncology
Heavy Chain Diseases
IgG Heavy Chain Disease (Gamma chain disease)
IgG heavy chain disease is generally similar to an aggressive malignant lymphoma but is occasionally asymptomatic and benign. IgG heavy chain disease occurs primarily in older men but can occur in children. Associated chronic disorders include Rheumatoid Arthritis (RA) , Common manifestations include lymphadenopathy and hepatosplenomegaly, fever, and recurring infections. Palatal edema occurs in about one quarter of patients. The CBC may show anemia, leukopenia, thrombocytopenia, eosinophilia, and circulating atypical lymphocytes or plasma cells. Diagnosis requires demonstration by immunofixation of free monoclonal heavy chain fragments of IgG in serum and urine. Of affected patients, half have monoclonal serum components>1 g/dL (>10 g/L), which are often broad and heterogeneous, and half have proteinuria>1 g/24 hours. Although heavy chain proteins may involve any IgG subclass, the G3 subclass is especially common. Bone marrow or lymph node biopsy, done if other tests are not diagnostic, reveals variable histopathology. The median survival with aggressive disease is about 1 year. Death usually results from bacterial infection or progressive malignancy. Alkylating agents,vincristine, or corticosteroids, and radiation therapy may yield transient remissions. 