While the simple detection of B-cell clonality does not imply B-cell malignancy, comprehensive analyses of B-cell clonality are crucial to investigate the pathobiology of B-cell lymphoproliferative disorders. Our recent studies in patients with Sjögren's syndrome have highlighted how multiple molecular analyses of B-cell clonality (Southern blot, polymerase chain reaction, single strand conformation polymorphism, and DNA sequence analysis) in prelymphomatous lesions may be of great value in helping to define the stages of progression towards low-grade malignancy. The study of T-cell expansion may also be important in investigations of the pathobiology of the different stages of B-cell lymphoproliferation (fully benign, pseudolymphomatous, or definitely malignant), which may still be T-cell-and antigen/ autoantigen-dependent.