Subclasses of extranodal oral B-cell lymphomas express cIgM, plasmacytoid, and monocytoid differentiation: A study of 10 cases

Abstract

Light microscopic and immunohistochemical findings in 10 extranodal oral B-cell lymphoproliferations are described. Three lymphomas were of the small lymphocytic/plasmacytoid type that also contained immunoblasts. Five lymphomas were monocytoid type with folded nuclei and pale-staining cytoplasm. Two lymphomas were of the large-cell type and contained multilobated blast cells, a low-grade neoplastic lymphoid component, and tumor plasma cells. All lymphomas were reactive with B-cell specific 4KB5, LN-2, L26, and LN-1 antibodies. There was a variable expression of intracytoplasmic μ heavy chain and monotypic κ or λ light chains with neoplastic lymphoplasmacytoid cells and plasma cells. These subclasses of primary oral lymphomas express the histologic and immunophenotypic likeness as well as the immunoreactive spectrum of parafollicular B cells. They may have an intimate morphogenetic association with that of the mucosa-associated lymphoid tissue lymphoma.