1. S.BELABBES,S.BELLASRI,S.CHAOUIR,T.AMIL,H.EN-NOUALI A RARE MEDIASTINUM TUMOR: THE PRIMARY LEIOMYOSARCOMA Department of Radiology, Military Teaching Hospital Mohammed V of Rabat. Morocco CH17

2. INTRODUCTION Primary leiomyosarcoma of the thorax is a rare malignant mesenchymatous tumor. It représents 1, 4% of all soft tissue sarcomas and 11% of mediastinal primary sarcomas Location by decreasing frequency: lung, mediastinum and pleura.

3. INTRODUCTION In most cases, leiomyosarcoma of the mediastinum grow at the expense of the esophagus or great vessels Exceptionally, they originate from the soft tissues of the mediastinum The posterior mediastinum is the preferential site of mediastinal leiomyosarcomas. The imagery is used to specify the characteristics of the lesion, its seat and extension

4. CLINICAL CASE A 35 years-old female presented with a gene respiratory lasting for a year and left shoulder pain radiating to the ipsilateral upper limb, without coughing or dyspnea or dysphagia. Clinical examination including pleuropulmonary is unremarkable

5. IMAGING DATA chest plain radiography shows a médiastino- pulmonary left opacity with net outer limit and lobed

6. IMAGING DATA CT scan shows an heterogeneous soft tissue mass of middle and posterior mediastinum, well limited, multilobed with intimate contact with the esophagus, the left subclavian artery, the aortic arch and left pulmonary pedicle

7. IMAGING DATA The patient was operated and the anatomopathologic examination found a primary leiomyosarcoma The magnetic resonance imaging performed to better study vascular relationships of the tumor, confirms the presence of a border security with the vascular structures of the mediastinum.

8. DISCUSSION Leiomyosarcoma is a rare mesenchymal tumor localized preferentially to the uterus and digestive tract In the mediastinum: leiomyosarcoma most often develops from smooth muscle tissue of the wall of the esophagus, vena cava, aorta, pulmonary artery or the trachea Very rarely, no origin can be individualized and leiomyosarcoma arises from the soft tissue of the visceral mediastinum

9. DISCUSSION The primary leiomyosarcoma of visceral mediastinum occurs most often in young adults. It can remain asymptomatic for a long time. It can reach a large size, and is manifested by signs of compression of adjacent organs depending on its location.

10. DISCUSSION In Imaging, it appears as a well circumscribed tissue mass which displaces or invades adjacent structures with areas of central hypodensities corresponding to areas of necrosis or hemorrhage The diagnosis of certitude is histological

11. DISCUSSION Surgical resection offers the only chance of cure The place of radiotherapy and chemotherapy is very limited without any consensus on their use. survival rate at five years: from 15 to 20% after complete surgical resection. Recurrences are possible and occur most frequently during the first two or three years after operation.

12. CONCLUSION Primary leiomyosarcoma of visceral mediastinum is an extremely rare malignancy it must be, however, be included in the differential diagnosis of mediastinal tumors in young adults The imagery is used to specify the characteristics of the lesion, its seat and relationship to surrounding structures especially vascular.