A study to evaluate the accuracy of ultrasound in the diagnosis of parotid lumps and to review the sonographic features of parotid lesions — results in 220 patients

Aim

To assess the accuracy of ultrasound in characterizing benign and malignant parotid lesions and to review their sonographic features.

Materials and methods

A retrospective analysis of 220 ultrasound examinations was undertaken in 220 patients who presented with palpable parotid lesions over an 11-year period and correlated with the clinico-histopathological findings. The original sonographic diagnosis was compared to the final histopathology and lesions characterized using previously established sonographic criteria.

Results

Histopathology results were available for all patients. Two hundred and one patients had focal lesions: 29 carcinomas, 21 lymphomata and 151 benign lesions (including 69 pleomorphic adenomas and 54 Warthin's tumours); 19 patients did not have focal lesions. The initial ultrasound report was indeterminate in 25/201 focal lesions. In the remaining 176 lesions, the sensitivity, specificity, and diagnostic accuracy for malignancy of ultrasound was 91, 93, and 93%, respectively. There were four false-negatives and nine false-positives with a crossover of apparently benign and malignant features. Pleomorphic adenomas and Warthin's tumours were poorly differentiated using ultrasound. Additional impalpable parotid lesions or adenopathy were detected in 44 patients using ultrasound.

Conclusion

Ultrasound is a valuable adjunct to clinical examination, accurately differentiating benign from malignant lesions and diagnosing non-focal disease. There is an overlap in features of pleomorphic adenomas and Warthin's tumours and of some benign and malignant lesions. Diagnostic ultrasound should be combined with needle biopsy in most patients to maximize diagnostic yield.