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Swelling of the parotid region is a frequent reason for consultation and the first clinical sign of both benign and malignant parotid tumors. These parotid tumors represent 80 % of tumors of the main salivary glands. They present a highly variable clinical and radiological picture and are known to have a wide histological diversity. Some histological types are rare entities found in the parotid gland, such as Ewing's sarcoma and lymphoepithelial cyst, the latter of which is often associated with HIV co-morbidity, and therefore requires careful and adequate therapeutic attitudes and strategies. We report two cases of parotid swelling revealing unusual pathologies: HIV and Ewing's sarcoma., Highlights • Swelling of the parotid region is a frequent reason for consultation. • Some histological types are rare entities found in the parotid gland. • The pathological examination of the surgical specimen provides a definitive diagnosis. • Age can be a concealing element, therefore a careful medical attitude is the key.

Purpose To characterize parotid tumors with dynamic susceptibility contrast perfusion-weighted magnetic resonance (MR) imaging and diffusion-weighted MR imaging. Material and methods Prospective study was conducted upon 48 consecutive patients (27 men, 21 women; aged 15-75 years; mean, 45 years) with parotid tumors that underwent dynamic susceptibility contrast perfusion-weighted MR imaging was performed after bolus injection of gadopentate dimeglumine and diffusion-weighted MR imaging. The dynamic susceptibility contrast percentage (DSC%) and apparent diffusion coefficient (ADC) values of parotid tumors were calculated and correlated with histopathological findings. Results The DSC% of malignant parotid tumors (33.53% ± 3.99%) was significantly different (P = 0.001) from that of benign parotid tumors (22.29% ± 4.13%). The threshold values of DSC% and ADC used in differentiating malignant from benign parotid tumors were 26.5% and 1.07 × 10 mm/s, respectively, with area under the curve (AUC) of 0.96 and 0.81, respectively. The DSC% of malignant parotid tumors was significantly different from that of Warthin tumors (P = 0.001). The cutoff DSC% used to differentiate malignancy from Warthin tumors was 26.9% with an AUC of 0.99. There was a significant difference in DSC% and ADC values between pleomorphic adenomas and Warthin tumors (P = 0.001). The threshold values of DSC% and ADC used in differentiating pleomorphic adenomas from Warthin tumors was 22.5% and 0.99 × 10 mm/s, respectively, with AUC of 0.88 and 0.98, respectively. Conclusions Dynamic susceptibility contrast-enhanced perfusion-weighted MR imaging and diffusion-weighted MR imaging are noninvasive promising methods that are used for differentiation of malignant from benign parotid tumors and for characterization of some benign parotid tumors.

Objectives The purpose of our study was to describe the various magnetic resonance (MR) findings of pleomorphic adenoma and to interpret these findings. Methods MR studies of 33 pleomorphic adenomas and 13 malignant tumors in the major salivary glands were reviewed. Results High signal intensity on short-inversion-time inversion recovery (STIR) and T2-weighted (T2W) images, progressive enhancement on dynamic MR images, and high apparent diffusion coefficient (ADC) values on diffusion-weighted (DW) images reflected myxoid-dominant components in pleomorphic adenomas. Hypercellularity with less-myxoid stroma showed reduced signal intensity on STIR and T2W images and also reduced ADC values on DW images, and the peak of time versus signal intensity curves (TICs) was reached earlier on dynamic MR images. Conclusions The MR images of hypercellularity components in pleomorphic adenoma overlap with those of malignant parotid tumors. Detecting myxoid components by STIR, T2W, DW, and dynamic MR images is useful for predicting whether salivary gland tumors are pleomorphic adenoma or not.

A review of the approximately 2000 parotid salivary gland tumors studied at the Columbia-Presbyterian Medical Center in New York from 1918 to 1978 showed that separate, synchronous neoplasms of different histologic types were found in the parotid gland in only 7 patients. In 6 of these patients, there was a clinically solitary mass; in the other patient, two separate nodules were palpated. In each case, subtotal or total parotidectomy was performed. On examination of the resected tissue, two separate nodules were identified grossly in three patients; in one, a benign mixed tumor and a mucoepidermoid carcinoma; in the second, a benign mixed tumor and a Warthin's tumor; and in the third, a mucoepidermoid carcinoma and a Warthin's tumor. In the remaining 4 patients, only one grossly evident tumor was found, including benign mixed tumor in 3 patients and a poorly differentiated adenocarcinoma in 1 patient. In each of these cases, the second tumor, discovered only microscopically, was a Warthin's tumor. Thus, in 6 of the 7 patients, the second neoplasm was a Warthin's tumor.

A 25-year experience with parotid tumors was reviewed. From a total of 250 neoplasms, 173 were histologically benign and 77 were malignant. Benign mixed tumors accounted for 59% of all lesions. Clinical parameters used to diagnose parotid neoplasms were found to be unreliable in determining whether a given tumor was benign or malignant. The mean age for malignant lesions was 10 years greater than for benign lesions. The phenomenon of malignant transformation of a benign tumor was considered in four patients. Complete surgical excision is the safest and preferred method for diagnosis. Preoperative needle or incisional biopsy are associated with a high degree of local recurrence. The appropriate management of any parotid tumor is predicated on special histological type. Local excision or enucleation no longer have a place in the surgical management of benign parotid tumors. Postoperative tumor recurrence and morbidity are directly related to awareness of surgical anatomy and pursuit of correct surgical techniques for adequate resection. The five-year recurrence rate for 102 benign mixed tumors was 6%. Recurrence in malignant tumors varied with specific histological types but was generally high. Five-year survival for all malignant parotid tumors was 48%.

Because of the anatomy of the deep lobe of the parotid and its restrictive boundaries, retromandibular tumors may be asymptomatic until reaching massive size. Removal by an intraoral approach may be not only disappointing but also disastrous, with disintegration of the tumor and generalized spillage in the wound. Our experience suggests that the best approach to any type of tumor in this region is through the upper lateral cervical tissues with consideration of a mandibular osteotomy if the tumor extends into the retropharynx or the nasopharynx. This review of 12 patients who required osteotomy describes a high success rate with minimal complications.