Evaluation of clinical and histopathological data in patients diagnosed with parotid gland tumor with systemic inflammation parameters and diffusion-weighted magnetic resonance images

Objective: Salivary gland tumors constitute 3% of all head and neck tumors. About 70% to 80% of these are located in the parotid gland. Benign-malignant differentiation and subgroup determination are important in terms of treatment planning and surgical method selection. This study aimed to evaluate the correlation of systemic inflammation markers and Apparent Diffusion Coefficient (ADC) measurement obtained by Diffusion-Weighted Magnetic Resonance Imaging with clinical and histopathological data in patients with a diagnosis of parotid gland tumor, and to evaluate their usability in the benign-malignant differentiation and subgroup determination. Methods: Patients who were diagnosed with parotid tumor between January 2013 and December 2021 and underwent surgery were screened retrospectively. Demographic data, smoking and alcohol use, preoperative hemogram and biochemistry data, pre- and postoperative pathological diagnoses and imaging data were obtained from patients who were both diagnosed and surgically performed in this clinic. Neutrophil Lymphocyte Ratio (NLR) and Platelet Lymphocyte Ratio (PLO) values were calculated. ADC maps were created from images obtained with neck MR images (Siemens Magnetom Aera, 1.5 Tesla). Measurements were made using 1 cm² circular areas of interest in solid regions of the tumors. Results: A total of 138 cases (108 benign [78.3%), 30 malignant [21.7%]) were included in the study. The most common benign tumor was pleomorphic adenoma, while the most common malignant tumor was mucoepidermoid carcinoma. While the mean age and PLR values of individuals with malignant tumors were higher than those with benign tumors, the lymphocyte count was found to be higher in patients with benign tumors. Tumor diameter, NLR and PLO values were different, while ADC values were similar. ROC analysis was performed to calculate the cutoff value in NLR and PLO parameters according to the benign-malignant distinction. NLR parameter was similar (p>0.05), PLO parameter was statistically different. The sensitivity rate for PLO was 62.1%, and the specificity rate was 63.9%. Analysis of histopathological subgroups showed that the ADC value was highest in pleomorphic adenomas and lowest in whartin tumors. The ADC values found in pleomorphic adenomas were significantly higher than both warthin tumors and mucoepidermoid carcinomas (p<0.05). The sensitivity rate of ADC value in differentiating pleomorphic adenoma from warthin tumor was 82.9%, and the specificity rate was 81.6%. Sensitivity rate was 76.9% and specificity rate was 76.3% in differentiating pleomorphic adenoma from mucoepidermoid carcinoma. Conclusion: This study showed that combining the quantitative values obtained from ADC measurements with conventional MR imaging findings may be a useful method in the differentiation of benign and malignant parotid tumors.We are in opinion that this may avoid use of invasive diagnostic methods. Considering the relationship between inflammation markers and cancer, we believe that using inexpensive, easily accessible and non-invasive markers such as PLR, NLR and lymphocyte count, especially before histopathological diagnosis, can be a guide in determining risk and predicting prognosis in this patient group. Keywords: Parotid neoplasms, benign, malign, systemic inflammation, diffusion magnetic resonance imaging