Salivary gland lymphoproliferative disorders: a Canadian tertiary center experience

Abstract

Salivary gland lymphoproliferative disorders (SGLD) are very rare tumors and clinicopathological data is sparse. In a Canadian series of 30 cases, extracted from the surgical pathology files of The Ottawa Hospital between 1990 and 2010, a clinical, histopathological, and immunophenotypic analysis was conducted. Tumors were staged using the Ann Arbor staging and classified using the World Health Organization 2008 classification. There were 15 salivary gland (SG) primary lymphomas with localized disease, predominantly mucosa associated lymphoid tissue type marginal zone lymphoma (MALT-L), but with a significant incidence of low grade follicular lymphoma (FL) and diffuse large B cell phenotype as well. There were 7 systemic SG lymphomas and 5 patients were diagnosed with lymphoproliferative disorders originating from intra-parotid lymph nodes. Finally, the remaining 3 cases represented reactive sialadenitis. A literature review was conducted and our primary lymphoma group was compared to those from other countries. SGLDs are predominantly B cell lymphomas that develop in older adults. Primary tumors, which have MALT-L and low grade FL characteristics, have a favorable survival, however MALT-L have a high rate of relapse. A minority of SG lesions are excised secondary to lymphomas that definitely arose from intra-parotid lymph nodes.

Fig. 1

Distribution of SGLD in excised lesions in patients presenting with enlarged salivary glands

Fig. 2

Histological features of primary malt lymphoma of the SG. a A low power view of a diffuse lymphocytic process infiltrating into a salivary gland (×40, H&E). b A high power view demonstrating typical lymphoepithelial lesion (×400, H&E). c Positive CD20 staining of the lymphocytes invading into the salivary glands, confirming the B-cell nature of the neoplasm (×400). d Diffuse kappa staining supporting the monoclonal nature of the neoplasm as well as perineural invasion (×200)

Fig. 3

Histological features of primary follicular lymphoma of the SG. a A low power view of a nodular lymphocytic process infiltrating into a salivary gland (×40, H&E). b A higher power view demonstrating lymphocytes admixed with salivary gland ducts (×200, H&E). c, d, and e Bcl-2, CD10, and CD20 immunohistochemical staining confirming the diagnosis of follicular lymphoma (×100)

Fig. 4

Histological features of primary diffuse large B-cell lymphoma of the SG. a A low power view of a diffuse lymphocytic process infiltrating into a salivary gland (×100, HPS). b A higher power view demonstrating sheets of large lymphocytes (×400, HPS). c High ki67 immunohistochemical staining, indicating a highly proliferative process (×400). d Positive CD20 immunohistochemical staining confirming the B-cell nature of the neoplasm (×400)