Abstract
A new case of µ-chain disease occurring in an African patient is described. The main clinical feature was a massive splenomegaly. Contrary to five previously reported cases, this patient was not affected with chronic lymphocytic leukemia, and vacuoles were not found in the cytoplasm of the bone marrow plasma cells. A considerable increase of the plasma volume was noted without hyperviscosity. The electrophoretic pattern showed an abnormal band in the α2 region. The anomalous protein was devoid of light chains and was present in the form of disulfide-linked polymers of incomplete µ-chains. The molecular weight of the monomer was approximately 58,000. The protein comprised the Fc fragment and a part of the Fd segment. Bence Jones protein was not found in the urine, and light chains were not present in the cells producing the µ-chain disease protein.
