الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Background:Teratomas are composed of tissues that are strange to the anatomic site of appearance and disposed in a disorganized fashion. Teratomas with malignant transformation contain malignant cells derived from mature tissues. Pluripotent cells are normally present in the gonads, and may also be found in abnormal sequestered midline embryonic rests. Accordingly, teratomas are found with decreasing frequency in the ovaries and testis, mediastinum, retroperitoneal space, sacrococcygeal zone, pineal and other intracranial locations . Exclusively presacral tumours present later than those with an external component, and have a higher prevalence of malignant transformation. They can present with chronic fistula, low back pain or obstructive symptoms of the gastrointestinal or genitourinary tracts. CT and MRI are the most important investigations for characterization of the mass, evaluation of its intrapelvic extension and rela¬tionship to other structures. Most commonly, teratomas appear as a complex mass with roughly equal amounts of solid heterogeneous and cystic areas with or without septations. They also frequently present as thick walled cystic masses, sometimes multiloculated. Invasion of adjacent structures, rather than simple displacement, sacral destruction and secondary findings such as locoregional lymph node and distant metastases are clearly indicative of malig¬nancy . The treatment for all sacrococcygeal teratomas consists of early and complete surgical excision with coccygectomy. This bone may contain a nidus of pluripotent cells that increase recurrence rates to 37% when not excised . If complete resection is accomplished, benign teratomas have a good prognosis and long-term survival is pos¬sible with malignant tumours.