Lymphoma and the parotid gland.

The rich parotid lymphatic network makes necessary the inclusion of benign and malignant lymphoid disease in the differential diagnosis of parotid swelling. This area is affected directly by lymphoma in many clinical situations and has an indirect relationship with lymphoma through Sjögren's syndrome. These associations can produce uncertainty about the etiology and significance of parotid masses. Patients with Sjögren's have a spectrum of lymphoproliferative disorders from benign lymphoepithelial disease (BLD) to lymphoma and a significantly greater incidence of the latter than the general population. Nine patients with lymphoma and also benign and malignant lymphoid disease in the parotid illustrate various diagnostic considerations. These include that both benign and malignant parotid lymphoid pathology are seen with systemic lymphoma, that lymphoma can co-exist with BLD, may be misdiagnosed as BLD, and can develop in the same gland after appearance of BLD.