Clinicopathologic study of mucosa-associated lymphoid tissue lymphoma of the salivary gland

Objective To study the histopathologic features and pathogenesis of mucosa- associated lymphoid tissue lymphoma (MALT-oma) of salivary glands. Methods Clinical data, paraffin-embedded sections, immunohistochemical slid es (SP method) and electron microscopic features of surgical specimens of 3 2 cases of salivary gland MALT-oma were studied. Results The patients were 27 males and 5 females, with a mean age of 54.76 years. The lesions were located in the parotid area in 17 cases, and in the submandibular gland in the remaining 15 cases. Much of the MALT-oma was re placed by infiltration of a great amount of centrocyte-like cells (CCL) as background and occasional large cells (centroblast- or immunoblast-like). I n MALT-omas "lymphoepithelial lesions" were present. Immunohistochemically, CD20 expression was found to be positive and CD45RO expression was negativ e in all MALT-omas. Conclusion Most of the MALT-omas are low grade malignant tumors and have a "homing back" phenomenon. The cases were managed by surgery and chemotherap y. In a few MALT- omas which turned into high grade malignant tumors, the p rognosis was poor. Acquired MALT may develop as a reaction to autoimmune di sease and infection. Hyper-immune reaction and MALT hyperplasia under stimu lation may result in myoepithelial sialadenitis and lead to MALT-oma of the salivary gland.