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WHO Classification of Tumours
Heavy chain diseases
Tumours of haematopoietic and lymphoid tissues


Definition

The heavy chain diseases (HCD) comprise 3 rare B-cell neoplasms that produce monoclonal heavy chains and typically no light chains. The monoclonal immunoglobulin component is composed of either IgG (gamma HCD), IgA (alpha HCD) or IgM (mu HCD). The heavy chain is usually incomplete and thus incapable of full assembly. Variably sized proteins are produced, that may not produce a characteristic serum protein electrophoresis peak, and require immunoelectrophoresis or immunofixation to detect. Alpha HCD is considered to be a variant of extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) . Gamma HCD is characterized by a lymphoplasmacytic population resembling lymphoplasmacytic lymphoma and Mu HCD typically resembles CLL ; however both are sufficiently distinctive to be considered separate entities.

Three types of heavy chain disease (HCD) have been recognized:
Alpha heavy chain disease / Immunoproliferative small intestinal disease
Gamma heavy chain disease
Mu heavy chain disease

> Related Topics
Introduction: Classification of lymphoid neoplasms


Structure of the immunoglobulin molecule in heavy chain disease
Structure of the immunoglobulin molecule in heavy chain disease