Radio-Histological Correlations of Parotid Tumors

surgery. The parameters studied were the patient’s age and sex, the motif of consultation. All of the clinical features of the swelling were studied and correlated with histology data. As for the imaging data, for each diagnostic method, we correlated the report of the radiologists concerning the nature of the tumor, to the results of the final histology, and we calculated the sensitivity, the specificity and the diagnostic efficiency of each diagnostic method. All our patients underwent surgical treatment on the tumor with or without associated lymph node surgery. MRI diagnostic values, sensitivity and specificity were calculated for three types of parotid lesions: pleomorphic adenoma, Warthin’s cystadenolymphoma, and malignant tumors. Correlations of 39 MRIs and 20 CT scans were performed. The objective of this work is to study the MRI characteristics of parotid tumors correlated with surgical histopathology (parotidectomy) and describe the typical imaging aspects of the main parotid tumors which helps to choose the adequate surgical management of these lesions and to provide the patient with the most accurate information adapted as much as possible to his pathology.

morphological and histological diversity, but it is the benign forms which predominate especially the pleomorphic adenoma [1]. The most frequent mode of revelation is a cervical swelling of the parotid space. Complementary examinations, in this case imagery, have become real diagnostic tools, on the one hand, to specify the exact location of the lesion, its extension to adjacent tissues and, on the other hand, to predict the malignant or benign nature of the lesion. Ultrasound, whether or not combined with fine needle aspiration, CT and MRI are the most frequently used methods. The objective of this work is to study the MRI characteristics of parotid tumors correlated with surgical histopathology (parotidectomy) and describe the typical imaging aspects of the main parotid tumors.

Materials and Methods
This is a retrospective study of 46 patients who were followed up and treated for a parotid tumor. The cases were collected over a period of 4 years, from January 2016 to July 2019, at the ENT surgery department at the Hassan II FES University Hospital. We only retained the files containing a computed tomography (CT) and / or magnetic resonance imaging (MRI) and whose nature of the tumor was confirmed by a histological study after parotid surgery. The parameters studied were the patient's age and sex, the motif of consultation. All of the clinical features of the swelling were studied and correlated with histology data. As for the imaging data, for each diagnostic method, we correlated the report of the radiologists concerning the nature of the tumor, to the results of the final histology, and we calculated the sensitivity, the specificity and the diagnostic efficiency of each diagnostic method. All our patients underwent surgical treatment on the tumor with or without associated lymph node surgery. MRI diagnostic values, sensitivity and specificity were calculated for three types of parotid lesions: pleomorphic adenoma, Warthin's cystadenolymphoma, and malignant tumors.

Results
The gender distribution was almost equivalent, with 25 women (54%) and 21 men (46%). The average age was around 39 years with extremes of 7 years and 87 years. All our patients presented a common symptomatology which is the parotid swelling with a size topathology The magnetic resonance imaging (MRI) plays a key role in the diagnosis and characterization of parotid tumors. It provides the clinician with anatomical information on the nature of the tumor being investigated. We have analyzed, through 46 cases, the radio-histological correlations of parotid tumors. our study includes 21 men and 25 women. The average age of our patients was 39 years. The most common histological types are pleomorphic adenoma (20 cases), cystadenolymphoma (7 cases) and cancers (9 cases). For our 46 patients, 39 MRIs and 20 CT scans were performed. The objective of this work is to study the MRI characteristics of parotid tumors correlated with surgical histopathology (parotidectomy) and describe the typical imaging aspects of the main parotid tumors which helps to choose the adequate surgical management of these lesions and to provide the patient with the most accurate information adapted as much as possible to his pathology. on the right side (56%). Among our 46 patients, 16 presented parotid pains, 4 a facial paralysis and four patients a reflex otalgia.
At the time of diagnosis, five of our patients presented a cervical lymph nodes. Examination of the stenon canal was normal in all of our patients. The anatomopathological study was mainly carried out on the operative piece, since the extemporaneous examination could only be carried out for a few patients due to technical constraints.
Benign tumors account for 80% of all of our patients, dominated mainly by pleomorphic adenoma followed by whartin tumor.
There were 8 cases of cancer that were of a diverse nature (Table   1)

Discussion
MRI currently appears to be the preferred examination in the exploration of the tumor pathology of the parotid glands, possibly combined with fine needle aspiration [2]. It is a noninvasive examination, allowing reconstruction in all planes and excellent tissue discrimination, however it is not tolerated by all patients, in particular claustrophobic ones, and its duration of acquisition remains significant with a weak bone characterization. Nevertheless, MRI is considered superior to computed tomography for the detection and analysis of a parotid tumor process. In clinical practice, the first step is to affirm an intraparotid tumor process.
The ultrasound of the parotid region is a rapid, accessible, noninvasive examination allowing good diagnostic sensitivity, with the possibility of acquisition in all planes. On the other hand, it is operator-dependent and offers poor accessibility for deep structures. Its sensitivity, specificity and relevance to tumors are 62, 91 and 85% respectively [3]. Some studies have analyzed the contribution of scintigraphy to 18-fluorodeoxyglucose. This examination does not seem to offer sufficient information for parotid tumor detection, even in image fusion with computed tomography [4].
The second step is to confirm the parotid origin of a large tumor or a tumor with a deep location. Three criteria allow MRI to confirm the parotid origin of the lesion: the medial displacement of the parapharyngeal fat; the lateral center of mass, relative to the parapharyngeal space; and the widening of the distance between the styloid process and the mandibular angle at the front [4]. During this stage, the needle aspiration is also discussed: some authors give relevance figures reaching 97% [5,6], others are more reserved obtaining lower results [7]. Some complications are possible such as a hematoma, facial paralysis [8] or even the implantation, however exceptional, on the puncture pathway of malignant tumor cells [9]. In all cases, this examination is highly operator dependent.  Conclusion MRI is currently the first line examination for the detection of a tumor in the parotid gland. It provides excellent spatial resolution and relevant tissue discrimination. It also makes it possible to confirm or deny a surgical indication for parotidectomy. Based on morphological and functional arguments, it gives a very specific diagnostic orientation to the anatomopathological results found in postoperative.