Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue type, referred to as mucosa-associated lymphoid tissue (MALT) lymphoma, arises as a low-grade B cell lymphoma associated with chronic inflammation. This disease is relatively rare and accounts for 0.3 percent of all malignant lymphomas. In this article, we report a case of MALT lymphoma coexisting with diffuse large B-cell lymphoma (DLBCL) arising in the submaxillary gland along with a literature review. A 67-year-old woman was referred to our hospital because of indolent right submandibular swelling. Palpable 30 × 25 mm mass was observed on the right submandible. Computed tomography (CT) showed a well-defined oval radiopaque mass measuring approximately 30 × 30 mm. We performed submaxillary gland resection with the patient under anesthesia for a suspected submaxillary gland tumor. A diagnosis of MALT lymphoma coexisting with DLBCL was made on the basis of the histopathological examination and immunohistochemical staining. As additional treatment, 3 cycles of rituximab with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) (R-CHOP) therapy were given after radiotherapy (36 Gy/20 fr) in accordance with the NCCN Guidelines. Currently, the patient is doing well with no recurrence.
