A Clinical Study of a Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma of Salivary Glands

Abstract

　Malignant lymphoma involving the salivary glands is a rare entity that accounts for only 1 to 4% of all salivary gland tumors. We have analyzed the clinical features of MALT lymphoma of the salivary glands in 7 patients whom we have treated in the past 10 years, including data from 43 patients in the literature. The most common symptom was persistent or progressive swelling of the salivary glands without pain or facial palsy.
　The affected glands were the unilateral parotid in 62%, the unilateral submandibular gland in 6.8%, and the bilateral parotid or submandibular gland in 6.8%. The salivary gland swelling as evaluated by MRI or ultrasonography consisted of a localized solitary tumor in 68.9%, multiple tumors in 10.3%, and diffuse swelling of the gland in 26.1%. In 24 out of 50 patients, MALT lymphoma developed on the basis of Sjögren's syndrome. As for diagnosis, malignant lymphoma was suspected only in 4 cases out of 11 (36.7%) based on the fine needle aspiration cytology. In all patients, a definitive diagnosis was obtained based on histopathological study of the localized tumor or the biopsy specimens. When patients with Sjögren's syndrome have developed persistent swelling of the salivary glands, it is necessary to rule out malignant lymphomas, especially MALT lymphoma, by combination of ultrasonography, MRI, FNA, and biopsy or open surgery depending on image findings.
　The treatment of MALT lymphoma has not yet been standardized because MALT lymphoma is a rare entity. The choice of initial treatment is important because it is related to its prognosis. If MALT lymphoma remains in a local site, we should undertake an operation or radiotherapy. If MALT lymphoma has dissemineated systemically, we should choose chemotherapy.