hematology and oncology
Heavy Chain Diseases
IgA Heavy Chain Disease (alpha chain disease)
IgA heavy chain disease is the most common heavy chain disease and is sometimes called Mediterranean lymphoma (immunoproliferative small intestinal disease). IgA heavy chain disease usually appears between ages 10 and 30 years and is geographically concentrated in the Middle East. The cause may be an aberrant immune response to a parasite or other microorganism. Villous atrophy and plasma cell infiltration of the jejunal mucosa are usually present and, sometimes, infiltration of the mesenteric lymph nodes. The peripheral lymph nodes, bone marrow, liver, and spleen usually are not involved. A respiratory tract form of the disease has been reported rarely. Common manifestations include fever, mild anemia, difficulty swallowing (dysphagia), recurrent upper respiratory infections, and an enlarged liver and spleen. Osteolytic lesions do not occur. Almost all patients present with diffuse abdominal lymphoma and Overview of Malabsorption . A complete blood count (CBC) may show anemia, Serum protein electrophoresis is normal in half of cases; often, there are increased alpha-2 and beta fractions or a decreased gamma fraction. Diagnosis requires the detection of a monoclonal alpha chain on immunofixation electrophoresis. This chain is sometimes found in concentrated urine. If this monoclonal alpha chain cannot be found in serum or urine, intestinal biopsy is required. The abnormal protein can sometimes be detected in intestinal secretions. The intestinal cellular infiltrate may be pleomorphic and not overtly malignant. Bence Jones proteinuria is absent. Treatment is with corticosteroids, cytotoxic drugs, and broad-spectrum antibiotics. The course is highly variable. Some patients die in 1 to 2 years, whereas others have remissions that last many years, particularly after treatment. 