Case vignettes and other brain teasers of monoclonal gammopathies.

There are a number of rare monoclonal gammopathies that do not have a characteristic laboratory, imaging, or pathologic study. Recognition requires keeping the specific syndrome in mind. This article reviews 6 rare syndromes associated with monoclonal proteins and gives specific "pearls" so a clinician can be certain not to overlook these important disorders that easily can be misdiagnosed as MGUS, Waldenstrom, and multiple myeloma.