Clinicopathologic Findings in T-Cell Large Granular Lymphocytic Leukemia-Associated Gamma Heavy Chain Disease.

Heavy chain diseases comprise a rare heterogeneous group of B-cell lymphoproliferative disorders characterized by the production of a truncated monoclonal immunoglobulin heavy chain without an associated immunoglobulin light chain. Gamma heavy chain disease often resembles lymphoplasmacytic lymphoma clinically and histopathologically. Its diagnosis requires the demonstration of monoclonal heavy chains in the serum or urine. We present the clinical and pathologic history of a 69-year-old woman who was incidentally identified with a monotypic B-cell population during routine flow cytometry for her untreated T-cell large granular lymphocytic leukemia. Further workup was consistent with a diagnosis of gamma heavy chain disease.