Parotid lymphomas--clinical and computed tomographic imaging features.

Objective: To review the clinical presentation and computed tomography (CT) imaging characteristics of all parotid lymphomas diagnosed at the study institution over a 7-year period.

Design: Retrospective chart review of parotid lymphomas diagnosed between 1997 and 2004.

Subjects: A total of 121 patients with parotid lesions were identified. After retrospective chart review, a total of 10 patients with histologically proven parotid lymphoma were included in the study, 8 of whom had CT scans available for assessment.

Results: Ten patients with histologically proven lymphoma of the parotid gland were identified from among 121 patients with parotid neoplasms, an incidence in this series of 8.3%. All lymphomas were of non-Hodgkin's type. All patients presented with a painless unilateral parotid swelling. Most patients had a short history of less than 4 months' duration, of whom 3 presented with a rapidly evolving swelling of less then 1 month's duration. No patient had a background of Sjögren's disease or any other autoimmune disorders. The commonest finding noted on CT was of a unilateral, single mass of relative soft-tissue homogeneity with poorly defined, indistinct tumour margins. Associated loco-regional lymphadenopathy was identified in 2 cases, 1 clinically and another radiologically; multiple ipsilateral lesions were noted in 2 cases. No cases of contralateral disease were observed.

Conclusion: Lymphoma has a clinical presentation similar to other neoplasms arising within the parotid gland. A unilateral, non-tender swelling was a universal finding. A history of less than 4 months may suggest the possibility of lymphoma. CT scanning is a useful adjunctive investigation to determine the site and extent of the disease, loco-regional nodal status and contralateral gland and neck status. Multifocality and associated adenopathy are associated with, but not exclusive to, parotid lymphoma. Although poor tumour boundary definition on CT imaging is a strong predictor of malignancy, no pathognomonic finding specific for lymphoma has been identified. The potential diagnosis of parotid lymphoma should be considered in all patients who present with a parotid mass.