Characterization of prelymphomatous stages of B cell lymphoproliferation in Sjögren's syndrome

OBJECTIVE: To determine whether the prelymphomatous stages of B cell lymphoproliferation in Sjögren's syndrome (SS) may be better characterized by the integration of clinical, pathologic, and molecular data, the latter focusing on the expansion, persistence, and dissemination of clonal B cells in the course of the disease. METHODS: Multiple tissue lesions (synchronous from different tissues and metachronous from the same tissue) were evaluated in biopsy specimens obtained from 6 consecutive patients with SS who had an associated lymphoproliferative disorder. Fully benign gastric lesions were evaluated in tissue from an additional 11 patients with SS who had no associated lymphoproliferative disorder. Multiple and complementary molecular analyses of B cell clonality were used: Southern blot, polymerase chain reaction, single-strand conformation polymorphism, DNA sequencing, and hybridization with clonospecific oligoprobes. All the patients were then strictly followed up for the appearance of lymphoma. RESULTS: Different scenarios of SS-associated B cell lymphoproliferation were identified: 1) the ongoing expansion of the same dominant clone, localized or disseminated, in tissue from 2 patients, 1 of whom later developed an overt B cell lymphoma; 2) different dominant clones in different synchronous or metachronous tissues from the remaining 4 patients with an associated lymphoproliferative disorder; and 3) small oligoclonal expansions in 7 of the 11 benign gastric lymphoid infiltrates. CONCLUSION: Prelymphomatous B cell lymphoproliferation in SS was better characterized following integration of the findings. The different types of B cell clonal expansion (oligoclonal or monoclonal, smaller or larger in size, fluctuating or established, localized or disseminated) may imply a different risk of lymphoma progression. An accurate clinical, histopathologic, and molecular characterization may therefore be crucial in future studies aimed at clarifying the pathobiology of SS-associated lymphoproliferation.