Atypical B cell dyscrasia with Bence-Jones proteinuria and intracellular retention of gamma-chains.

A case of atypical B cell dyscrasia is described. The patient presented with a history of weakness, bone pain, and bleeding. A K-type paraprotein was found in serum and urine. The histology of bone marrow was that of a malignant lymphoma, but no enlargement of peripheral lymphoid organs was detectable. Peripheral blood lymphocytes were increased in number and included two populations of immature cells, one lymphoid and the other lymphoplasmocytoid. Immunofluorescent staining showed both populations to contain K and gamma chains in their cytoplasm. The clinicopathological heterogeneity suggests a malignant clone of B cells undergoing incomplete maturation, with arrest at different stages of the cell cycle.