Role of ultrasound in the assessment of benignity and malignancy of parotid masses

Abstract

Objectives: This study aimed to investigate the value of ultrasound in the identification of benign and malignant parotid masses.

Methods: Data of 189 patients with parotid gland masses undergoing ultrasound-guided fine-needle aspiration (FNA), core biopsy or surgery were reviewed retrospectively and the presumed sonographic diagnoses were compared with the histopathology. The sensitivity, specificity and accuracy of sonographic diagnoses were assessed and the sonographic characteristics of those lesions, including shape, margin, echogenicity, echotexture and vascularization, were studied.

Results: Of the 189 patients, the final pathological diagnosis included 18 malignant tumours and 171 benign masses; the presumed sonographic diagnoses showed 165 cases as benign and probably benign masses (11 cases were confirmed malignant, 154 cases benign) and 24 cases were diagnosed as probably malignant and malignant masses (7 cases were confirmed malignant, 17 cases benign). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of ultrasound for the diagnosis of parotid gland masses were 38.9%, 90.1%, 29.2%, 93.3% and 85.2%, respectively, and accuracy for malignant masses was 20%. The sonographic characteristics of parotid masses between benign and malignant lesions had no significant differences. The parotid gland masses in this study included pleomorphic adenoma, Warthin's tumour, retention cyst, haemangiomas, chronic granuloma, lymphoma, fibrolipoma, abscess, basal cell adenoma, oncocytoma, lymphatic tuberculosis, myoepithelioma, neurilemmoma, mucoepidermoid carcinoma, adenoid cystic carcinoma, alveolar soft part sarcoma and retinal blastoma (metastasis).

Conclusions: It is challenging to use sonography for differentiating between benign and malignant parotid gland masses. To make a definite diagnosis, ultrasound-guided FNA or core biopsy is advocated.

Figure 1

Sonographic image shows a heterogeneous hypoechoic ovoid mass in the left parotid in a 36-year-old male with well-defined margin, posterior echogenicity enhancement and mild edge refraction. The presumed diagnosis was benign lesion and the pathological diagnosis was pleomorphic adenoma

Figure 2

Sonographic image shows a heterogeneous hypoechoic ovoid mass in the left parotid in a 68-year-old female with punctate calcifications, circumscribed margin, posterior echogenicity enhancement and distinct edge refraction. The presumed diagnosis was benign lesion and the pathological diagnosis was Warthin's tumour

Figure 3

Sonographic image shows a heterogeneous hypoechoic ovoid mass in the right parotid in a 47-year-old male with circumscribed margin, posterior echogenicity enhancement, distinct edge refraction and much vascularization in colour Doppler imaging. The presumed diagnosis was probably benign lesion and the pathological diagnosis was oncocytoma

Figure 4

Sonographic image shows a heterogeneous hypoechoic lobulated mass in the left parotid in a 52-year-old female with circumscribed margin, posterior echogenicity enhancement, distinct edge refraction and fair vascularization in colour Doppler imaging. The presumed diagnosis was probably benign lesion and the pathological diagnosis was mucoepidermoid carcinoma

Figure 5

Sonographic image shows a heterogeneous hypoechoic ovoid mass in the right parotid in a 27-year-old male with punctate calcifications, well-defined margin, posterior echogenicity enhancement and distinct edge refraction. The presumed diagnosis was probably malignant lesion and the pathological diagnosis was lymphatic tuberculosis