Primary salivary gland lymphoma among Japanese: A clinicopathological study of 30 cases

To clarify the clinicopathological findings of primary salivary gland lymphoma as defined by the World Health Organization (WHO) classification, 30 Japanese patients with this disease were studied. The male to female ratio was 1:1.7 and median patient age was 5 7 years. The parotid gland (n = 22) was involved most frequently, followed by the submandibular gland (n = 5) and minor salivary gland (n = 3). Twenty-four (80%) cases demonstrated Stage IE, whereas only six (20%) had Stage IIE-1. None of the 30 cases had B symptoms or a poor performance status. The 5-year overall survival of 31 cases was 96% and 5-year failure-free survival was 77%. Histologically, 15 cases were mucosa-associated lymphoid tissue (MALT) lymphoma, seven were follicular lymphoma (FL), and six were diffuse large B-cell lymphoma (DLBCL) + MALT lymphoma and only two were DLBCL without a MALT lymphoma component. MALT lymphoma is the most frequent type of primary salivary gland lymphoma. However, FL comprised 20% of primary salivary gland lymphoma. The majority of the primary salivary gland DLBCL appear to arise from MALT type lymphoma. When appropriate therapy for histologic subtype is used, outcome of the primary salivary gland B-cell lymphoma appears excellent whether histologically indolent or aggressive.