ARRS 2022 Abstracts

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E1808. The Invasion of Fat, Silent and Dangerous: A Radiologic-Pathologic Correlation of the Liposarcoma in Usual and Unusual Locations
Authors
  1. Hector Culebro Bermejo; Hospital Star Medica Tlalnepantla
Background
Retroperitoneal sarcomas constitute 0.1–0.2% of all malignant tumors. Only 10–20% of sarcomas are located in the retroperitoneum. Approximately 80% of retroperitoneal neoplasms are malignant. Most are of mesodermal origin; liposarcomas, leiomyosarcomas, and pleomorphic sarcomas constitute up to 80% of these tumors.

Educational Goals / Teaching Points
The goals of this exhibit are as follows. Describe the general characteristics and subtypes of the liposarcoma. Review liposarcoma subtypes and imaging characteristics for each subtype. Know clinical features and pathogenesis of liposarcoma. Identify the imaging characteristics for each liposarcoma subtypes and all the radiological modalities (radiography, CT, MRI, PET-CT, SPECT-CT, and others). Associate the clinical presentation, the radiological studies, and the histopathological result. Lastly, discuss the appropriate management and follow up of the liposarcoma based on recent literature guidelines and expert opinions.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Ultrasound has a more limited role in the evaluation of the retroperitoneum, but we cannot forget that it will often be the first modality used in patients with non-specific abdominal symptoms, thus ultrasound is the technique that alerts about the existence of a mass. Due to its greater availability, ultrasound will also be frequently used as a guide for performing percutaneous biopsies. CT is the most commonly used imaging modality. In most cases, it is less sensitive than MRI to motion artifacts and allows a better definition of the relationship of the tumor to the abdominal organs. The abdominal-pelvic study allows to assess the local and hepatic extension and the thoracic to rule out pulmonary metastases. It is generally performed after the administration of intravenous and digestive contrast. The study without contrast is not essential unless a retroperitoneal hematoma is suspected. Multiplanar reconstructions are useful for pinpointing anatomical relationships. MRI is generally reserved to solve specific problems such as vascular or spinal invasion and is especially useful in the pelvic location of the tumor. PET-CT is used in an effort to assess tumor grade and especially in the evaluation of recurrences.

Conclusion
The management of retroperitoneal sarcomas must be multidisciplinary. The radiologist plays a fundamental role in local and remote staging, establishing resectability criteria with curative intentions, and is capable of performing a safe biopsy and detecting early recurrences in the follow-up.