[Primary MALT-type malignant lymphomas of the salivary glands]

Six cases of primary extranodal lymphomas in big salivary glands, which met criteria of MALT lymphoma, were investigated with the aid of antibodies against Ig, light chains, LCA and EMA, in addition in two cases against Ig heavy chains and with antibodies KL-1 and VCHL-1. All the tumours had centrocytoid morphological features, one of them showed signs of focal blastic transformation into centrocytoid centroblastoma. Tumour cells showed twice plasmacytic and three times plasmacytoid differentiation with intracytoplasmic Ig monoclonality (once IgM/kappa, once IgA/kappa, three times kappa positivity). They were positive in reaction against epimyoepithelial proliferation. A picture of myoepithelial sialoadenitis with partial lymphomatous infiltration prevailed in two cases and a lymphoma picture with remnants of sialoadenitis in three cases. Features of inflammatory process were lacking in a case with blastic transformation. There is a dispute whether features of sialoadenitis belong to the defining criteria of MALT type lymphoma or can disappear during blastic transformation of a low grade malignant lymphoma.