Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content ++ DEFINITION ++ The heavy-chain diseases (HCDs) are neoplastic disorders of B cells that produce monoclonal immunoglobulins (Ig) consisting of truncated heavy chains without attached light chains. The diagnosis is established from immunofixation of serum, urine, or secretory fluids in the case of α-HCD or from immunohistologic analysis of the proliferating lymphoplasmacytic cells in nonsecretory disease. In decreasing order of incidence, HCD involves synthesis of defective α, γ, or μ heavy chains. There is a high frequency of autoimmune disorders preceding or concurrent with the diagnosis of HCD, particularly γ-HCD. Table 71–1 summarizes the clinical features of the three types of HCD. ++Table Graphic Jump LocationTABLE 71–1SUMMARY OF FEATURES OF THE HEAVY-CHAIN DISEASESView Table|Favorite Table|Download (.pdf) TABLE 71–1 SUMMARY OF FEATURES OF THE HEAVY-CHAIN DISEASES Type of Heavy-Chain Disease Feature α γ μ Year described 1968 1964 1969 Incidence Rare Very rare Very rare Age at diagnosis Young adult (<30 years) Older adult (60–70 years) Older adult (50–60 years) Demographics Mediterranean region Worldwide Worldwide Structurally abnormal monoclonal protein IgA IgG IgM MGUS phase No Rarely Rarely Urine monoclonal light chain No No Yes Urine abnormal heavy chain Small amounts Often present Infrequent Sites involved Small intestine, mesenteric lymph nodes Lymph nodes, marrow, spleen Lymph nodes, marrow, liver, spleen Pathology Extranodal marginal zone lymphoma (MALT or IPSID) Lymphoplasmacytoid lymphoma Small lymphocytic lymphoma, CLL Associated diseases Infection, malabsorption Autoimmune diseases None Therapy Antibiotics, chemotherapy Chemotherapy Chemotherapy CLL, chronic lymphocytic leukemia; Ig, immunoglobulin; IPSID, immunoproliferative small intestinal disease; MALT, mucosa-associated lymphoid tissue; MGUS, monoclonal gammopathy of undetermined significance.Adapted with permission from Witzig TE, Wahner-Roedler DL: Heavy chain disease. Curr Treat Options Oncol 3:247, 2002.Source: Williams Hematology, 8th ed, Chap. 112, Table 112–1, p. 1710. ++ ETIOLOGY AND PATHOGENESIS ++ The etiology of γ-HCD and μ-HCD is unknown. In α-HCD, the lymphoplasmacytic infiltration of the intestinal mucosa is thought to be a response of the alimentary tract immune system to protracted luminal antigenic stimulation. ++ CLINICAL AND LABORATORY FEATURES ++ γ-HCD ++ Median age at presentation is in the late sixties. Clinical features different from those of myeloma because renal disease and osteolytic lesions rarely occur. Has various clinical and pathologic features that can be divided into three broad categories: — Disseminated lymphoproliferative disease. — Localized proliferative disease: Approximately 25 percent of patients. — No apparent proliferative disease: Approximately 15 percent of patients. Most γ-HCD proteins are dimers of truncated heavy chains without associated light chains. The serum protein electrophoretic pattern is extremely variable, but a monoclonal peak is detected in over two-thirds of patients. The median value of the monoclonal spike at diagnosis in one study of 19 patients was 1.6 g/dL. The amount of HCD protein in the urine usually is small (<1 g/24 h), but may reach 20 g/24 h. Patients commonly have moderate, normochromic, normocytic anemia. Autoimmune hemolytic anemia has ... GET ACCESS TO THIS RESOURCE Sign In Username Error: Please enter User Name Password Error: Please enter Password Forgot Username? Forgot Password? Sign in via OpenAthens Sign in via Shibboleth Get Free Access Through Your Institution Contact your institution's library to ask if they subscribe to McGraw-Hill Medical Products. What is MyAccess? Create a FREE MyAccess profile to: Use this site remotely Bookmark your favorite content Track your self-assessment progress and more!