Dissemination of a Sjögren's syndrome–associated extranodal marginal‐zone B cell lymphoma: Circulating lymphoma cells and invariant mutation pattern of nodal Ig heavy‐ and light‐chain variable‐region gene rearrangements

Abstract

Both the genesis and outgrowth of extranodal marginal-zone B cell lymphomas (MZLs) of the mucosa-associated lymphoid tissue (MALT) type are generally thought to represent antigen-driven processes. We undertook this study to analyze lymphoma progression and dissemination outside of the MALT-type lesions. Histopathologic and Ig heavy- and light-chain variable-region gene (V(H/L)) analyses were performed in sequential tissue samples from a patient with primary Sjögren's syndrome (SS) with glandular (parotid) manifestations and subsequent nodal dissemination of a low-grade MZL. This MZL expressed a CD20+,CD27+,sIgM/kappa+,IgD-,CD5-,CD10-,Bcl-6-,CD23-,p53-,p21-,MDM2- phenotype and mutated V(H)1-69/D2-21/J(H)4alpha-V(kappa)A27/J(kappa)2 Ig rearrangements. Notably, circulating lymphoma cells from the parotid glands occurred transiently in the patient's blood, as detected by single-cell polymerase chain reaction. In addition, 2 minor B cell clones (clones 2 and 3, with V(H)3-07/D3-22/J(H)3b-V(lambda)3L/J(lambda)2/3 and V(H)3-64/D3-03/J(H)2-V(kappa)A19/J(kappa)2 rearrangements, respectively) were also detected in the parotid glands and blood, and 1 of these (clone 2) was also detected in the lymph nodes. Ig V(H/L) analyses revealed ongoing (antigen-driven) mutations of the glandular lymphoma rearrangements, but an invariant mutation pattern of their nodal counterparts. These data indicate coexpansion and transient (re)circulation of the lymphoma clone and 2 additional glandular B cell clones in a primary SS-associated extranodal MZL. Combined histologic and molecular features of the nodal lymphoma subclone reflect a process of "follicular colonization" that eventually froze the mutation machinery after accumulation of additional (antigen-driven) Ig V(H/L) mutations.