Extrasalivary lymphoma development in Sjögren's syndrome: clonal evolution from parotid gland lymphoproliferation and role of local triggering.
OBJECTIVE
To characterize Sjögren's syndrome (SS)-related B cell lymphoproliferation at the premalignant stage and during the evolution to B cell lymphoma, and to better understand the pathobiologic mechanisms associated with clonal expansion and the possible influence of different microenvironments on neoplastic transformation.


METHODS
We analyzed sequential parotid and lung biopsy specimens that were obtained from a single patient with SS at multiple time points over a 7-year period. Polymerase chain reaction DNA amplification, cloning, and sequencing of the immunoglobulin heavy chain variable region showed clonality, somatic mutations, intraclonal heterogeneity, and genealogic relationships of the B cell clones in the different biopsy specimens.


RESULTS
The evolution of a nonmalignant B cell clone that was present in the parotid gland and evolved into a B cell lymphoma was documented. During such a process, one subclone was selected that accumulated somatic mutations in a pattern consistent with the preservation of antigen receptor functionality, possibly attributable to continued hypermutation and selection. Intraclonal diversity indicated the presence of local triggers in both the parotid and lung microenvironments.


CONCLUSIONS
Molecular followup of B cell lymphoproliferation in SS, from nonmalignant stage to overt B cell lymphoma, indicated a role for B cell receptor engagement in clonal survival. The outgrowth of one subclone, with malignant transformation in the lung, a target organ different from the initial site of the lymphoproliferative process (the parotid gland), indicates that resident stimuli in different microenvironments may locally sustain ongoing lymphoproliferation and B cell transformation.
Gasparotto
Daniela
D
Centro di Riferimento Oncologico, Istituto di Ricovero e Cura a Carattere Scientifico, Aviano, Italy.
De Vita
Salvatore
S
De Re
Valli
V
Marzotto
Alessandra
A
De Marchi
Ginevra
G
Scott
Cathryn Ann
CA
Gloghini
Annunziata
A
Ferraccioli
Gianfranco
G
Boiocchi
Mauro
M
D000328:Adult; D002455:Cell Division; D002999:Clone Cells; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics; D016393:Lymphoma, B-Cell / Q000150:complications* / Q000235:genetics / Q000473:pathology; D010306:Parotid Gland / Q000473:pathology*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D012334:RNA, Neoplasm / Q000032:analysis; D012859:Sjogren's Syndrome / Q000150:complications* / Q000235:genetics / Q000473:pathology
D004273:DNA, Neoplasm; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D012333:RNA, Messenger; D012334:RNA, Neoplasm