Lymphoma

Epidemiology

Lymphoma of the parotid gland may arise within the parotid parenchyma (primary) or within the intraparotid lymph nodes (secondary). Primary lymphoma of the parotid gland is very rare and accounts for < 5% of parotid tumors. Primary parotid lymphoma is felt to be part of mucosal associated lymphoid tissue lymphomas (MALT-omas). These lesions may involve any portion of the gastrointestinal tract where lymphoid tissue is part of the mucosal defense system. Lymphoid tissue is normally present in the parotid gland and absent in adult submandibular and sublingual glands. As a result, 80% of reported salivary gland involvement of primary lymphoma occurs in the parotid gland and 20% involves the submandibular glands.

Secondary lymphoma is also rare, with the reported incidence ranging between 1 and 8% of the cases of lymphoma. There is an association between both Sjögren’s syndrome and Waldenström’s macroglobulinemia and secondary parotid lymphoma.

Clinical Findings

Women are at slightly greater risk with the majority of patients presenting after the age of 50. Patients typically present with a painless parotid-region mass. The facial nerve is usually normally functioning.