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

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 mu heavy chain and monotypic kappa or lambda 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.