A Case of MALT Lymphoma in the Parotid Gland

We report a case of MALT (mucosa-associated lymphoid tissue) lymphoma in the parotid gland. MALT lymphoma, an extranodal low-grade lymphoma arising in the stomach, salivary gland or thyroid gland is caused by chronic inflammation such as chronic gastritis, Hashimoto’s disease and Sjogren syndrome. An optimal therapy has not been established for MALT lymphoma of the salivary gland. The patient was a 68-year-old woman with swelling of the left parotid gland. A left parotid tumor was diagnosed by CT and MRI, and was treated surgically. The postoperative pathological diagnosis of the left parotid tumor was MALT lymphoma: there were centrocyte-like cells, plasma cells with ditcher bodies, and a lymphoepithelial lesion. Immunohistologic examination showed that the MALT lymphoma was positive for CD20, CD79α and bcl-2, and negative for CD3, CD5 and CD10. She felt mouth dryness. The left parotid gland was found to have become atrophic by MRI, and SS-A antibodies were noted on blood testing. Further, pathological tissue typical of Sjogren’s syndrome was noted in her salivary gland operatively. So a diagnosis of Sjogren’s syndrome was made, and MALT lymphoma was believed to have developed from Sjogren’s syndrome. There was no evidence of recurrence 12 months after the operation