1. IMAGING CONTRIBUTION IN CHARACTERIZATION OF PAROTID GLAND WARTHIN’S TUMOR: ABOUT THREE CASES. K.KNAISSI, I.KECHAOU, R.DAOUD, F.JABNOUN, K. BOUZAID Department of Radiology, MT Maamouri Hospital, Nabeul, Tunisia HN7

2. INTRODUCTION Warthin’s tumor (benign cystadenolymphoma) is the second most common salivary gland tumor after pleomorphic salivary. The exact pre-operative diagnosis of Warthin’s tumor remains a major challenge, it allows patients to avoid a total parotidectomy. The purpose of our work is to illustrate the imaging features of this tumor.

3. METHODS AND MATERIELS Retrospective study of 3 patients distributed in 2 men and 1 woman with a mean age of 60 years. The main reason for consultation was a painless parotid swelling lasting for several months. Three patients underwent cervical ultrasonography. One had a CT imaging both pre- and post-contrast studies. One had MR imaging including axial, coronal T1, T2 weighted and contrast enhanced. The diagnosis of warthin’s tumor was mentioned in only one case. All patients underwent parotidectomy with histological confirmation of diagnosis of warthin’tumor.

4. RESULTATS PATIENT 1: An 69 –year-old women presented with mass of the inferior pole of right parotid gland. Parotid ultrasound demonstrating a well circumscribed oval lesion with heterogeneous appearanceand small areas of kystisation.

5. RESULTATS PATIENT 2: An 62 year old man presented with right parotid mass. Parotid ultrasound demonstrating a well circumscribed oval lesion with cystic (arrow) an solid portions (large arrow).

6. Axial T1-weighted (A), axial T2-weighted (B) and axial T1-weighted (C) contrast enhanced fat suppressed MR image. A: multifocal hyperintense small cysts (arrow) and hypointense large cyst with solid stroma (large arrow). B: the solid stroma shows low signal intensity (arrow)and the cystic portion shows high signal intensity (double arrow). C: after gadolinium enhancement, the solid stroma shows faint enhancement (arrow). Fig 3(A)Fig3(B) Fig 3(C)

7. RESULTATS PATIENT 3: An 81 year old man, presnted with right parotid mass. Parotid ultrasound demonstrating a well circumscribed oval lesion with cystic (arrow) an solid portions (large arrow).

8. Cervical CT: axial slices pre- and post-contrast well-circumscribed lesion with cystic and solid components. Enhancement after contrast administration is relatively poor.

9. DISCUSSION Warthin tumor generally has been regarded as the second most common benign tumor of the parotid gland after pleomorphic adenoma. It occurs largely in middle-aged and older men and usually in the parotid gland or periparotid region, mostly involving the inferior pole of the gland. It is clinically important to determine preoperatively this diagnosis because exofacial parotidectomy is recommended in this case and only 2% recurrence is reported. Imaging (US, CT and MR imaging) provides a diagnostic approach.

10. DISCUSSION the best arguments in favor of the diagnosis of Warthin’s tumor are: - location in the lower pole of the gland observed in three patients of our series. - bilaterality and multiplicity of lesions. - the existence of a cystic portion.

11. Fig. 1. Classification of the shape of Warthin’s tumor is presented. Type 1 tumors are entirely cystic masses (arrow) with a peripheral solid enhancing rim (A). Type 2 tumors are solid and cystic masses; a solid mass with a large cystic portion (type 2A, arrow) (B) and a mainly solid mass with small cysts (type 2B, arrow) (C). Type 3 tumors are entirely solid enhancing masses (arrow) (D). DISCUSSION

12.  Sonography is the first step, especially for lesions in the superficial lobe of the parotid gland. It can be used to distinguish solid from cystic, guide fine-needle aspiration.  three patients in our series had an ultrasound first intension showing a single lesion of the right parotid in three cases and cystic portion which is of variable size. DISCUSSION

13.  CT is the method of choice in patients suspicious for inflammatory disease (abscess, calculi, major salivary duct dilatation, and acute inflammation) or in patients with contraindication for MR imaging.  For CT imaging, both pre- and post-contrast studies must be performed.  CT shows a double component of the tumor tissue and cystic with enhancement of tissue portion post contrast study.

14.  MR imaging (MRI) is the method of choice for patients with palpable masses and a strong suspicion that the lesion is neoplastic.  MRI gives information on the exact localisation and extent of the lesion, addresses neighbouring structures, and allows perineural spread, bone invasion and meningeal infiltration to be assessed. DISCUSSION

15. MRI findings of Warthin’s tumor is related to the presence of a double epithelial and lymphoid contingeant.  Intermediate signal intensity of the stroma seen on both T1 and T2 weighted (high cellular epithelial components).  High or heterogeneous signal intensity of the stroma seen on T2 weignted ( mixed epithelial tissue with lymphoid proliferation).. DISCUSSION

16.  Focal hyperintense areas seen on T1 weighted (semisolid cysts that contain proteinaceous fluids with cholesterol crystals).  Dense nodular enhancement at the peripheral stroma (mitochondriarich oncocytes).  High signal intensity on diffusion-weighted with lower ADC value.. DISCUSSION

17. Recently, a dynamic contrast-enhanced MRI (DCE-MRI) have shown promising results in the differentiation between benign and malignant salivary gland tumours. Malignant salivary gland tumours can be differentiated from pleomorphic adenomas but not from Whartin tumours using DCE-MRI at a time of peak enhancement of 120 s. A washout ratio of 30% enabled the additional differentiation between malignant and Whartin tumours.

18. DISCUSSION Using time-signal intensity curves on the basis of time to peak enhancement of 120 s and a washout ratio of 30% had high sensitivity (91%) and specificity (91%) in the differentiation between benign and malignant tumours.

19. Type B: Warthin’tumor Type A: Pleomorphic adenoma Type C: Malignant tumours

20. CONCLUSION warthin’s tumor is frequently seen in the parotid superficiel lobe of older males with a higher bilateral and multiple tendency. Warthin’s tumor shows cystic portions with papillary projections at the wall on CT images and focal high signal intensity on T1- weighted images with dense nodular enhancement on MR images. A dynamic contrast-enhanced MRI (DCE-MRI) show precocious enhancement with fast washout.

21. BIBLIOGRAPHY Warthin tumor of the parotid gland: diagnostic value of MR imaging with histopathologic correlation. AJNR Am J Neuroradiol 25: 1256-1262, August 2004. Mitsuaki Ikea, Ken Motoori, Toyouki Hanazawa, Yuichiro Nagai, Seiji Yamamoto. Warthin’s tumour: a retrospective case series. The british Journal of Radiology, 82 (2009), 916-919. TR Taylor, N J A Cozens, I Robinson. Warthin’s Tumor of the parotid gland: CT and MR features. J Korean Soc Radiol 2009: 61; 17-22. Yun Hee Lee, In Kyu Yu, Byung Hee Lee. Imaging of salivary gland tumours. Cancer Imaging (2007) 7, 52-62. Harriet C. Thoeny.