14 Metastatis of Soft Tissue Sarcomas Fethi Derbel et al. * Department of Surgery, University Hospital Sahloul, Sousse Tunisia 1. Introduction Although soft-tissue sarcomas account for <1% of all malignancies, they represent a high percentage of cancer-related deaths worldwide [1]. These tumors may arise in virtually any anatomic site, but most originate in an extremity (59%), the trunk (19%), the retroperitoneum (15%), or the head and neck (9%) [2]. Currently, more than 50 histologic types of soft tissue sarcoma have been identified, but the most common are malignant fibrous histiocytoma (28%), leiomyosarcoma (12%), liposarcoma (15%), synovial sarcoma (10%), and malignant peripheral nerve sheath tumors (6%) [3]. Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood. 2. The role of the pathology As part of the evaluation by a specialist multidisciplinary team, accurate histological characterisation is essential before initiating treatment. The mainstay of diagnosis is histological interpretation±immunohistochemistry, although cytogenetic and molecular genetics investigations and, occasionally, electron microscopy are useful ancillary tools. Cytological analysis of fine-needle aspirates has a limited role in primary diagnosis, but can be used to confirm recurrent disease, or nodal metastases. The histopathology report is an interpretation based on tumour morphology and immunoprofile in the available sampled tissue, and clinicopathological correlation is mandatory. Diagnosis is most frequently made on needle core biopsy material, and tumour subtype and grade can be determined in about 80% of core biopsies [4], although pathologists experienced in examining soft tissue tumours have a diagnostic accuracy of 95-99% [4,5]. The amount of tissue can be a limitation, as the biopsy may not represent the entire, frequently heterogeneous tumour, or may miss the tumour. For this reason, correlation * Sonia Ziadi¹, Medi Ben Hadj Hamida², Jaafar Mazhoud², Mohamed Ben Mabrouk², Abdallah Mtimet², Sabri Youssef², Ajmi Chaouch³, Ali Ben Ali², Ibtissam Hasni⁴, Mrad Dali Kaouthar⁴, Jemni Hela⁴, Moncef Mokni¹ and Ridha Ben Hadj Hamida² 1 Department of Pathology, University Hospital Farhat Hached, Sousse, Tunisia 2 Department of Surgery, University Hospital Sahloul, Sousse, Tunisia 3 Department of Anesthesiology and Intensive Care, University Hospital Sahloul, Sousse, Tunisia 4 Department of Medical Imaging, University Hospital Sahloul Sousse, Tunisia