Review Question - QID 217324

Myxoid liposarcomas display an unusual metastatic disease pattern with metastases showing up in the abdomen, retroperitoneum, and soft tissues of other extremities. It is, therefore, prudent to order a CT of the chest, abdomen, and pelvis as part of the routine surveillance pattern in the postoperative setting.

Liposarcomas are the second most common soft tissue neoplasm (undifferentiated pleomorphic sarcoma is most common), with approximately 30% of them being myxoid liposarcoma or round-cell liposarcoma. Unlike other bony and soft tissue sarcomas, myxoid and round cell liposarcomas have the ability to metastasize to extrapulmonary sites, necessitating surveillance studies including the chest, abdomen, and pelvis. Physical examination is typically sufficient to detect extremity metastases. Treatment is primarily surgical with wide resection, while neoadjuvant or adjuvant radiation is determined on a case-by-case basis. Chemotherapy plays a limited role but may be used in recurrent disease or in patients with metastases.

von Mehren et al published NCCN clinical practice guidelines for soft tissue sarcoma. They recommend chest/abdomen/pelvis CT scans as part of the initial and surveillance workup in patients with myxoid and round-cell liposarcomas. They also recommended MRI of the entire spine as myxoid/round-cell liposarcoma has a higher predilection for spinal metastases, but they did not give a surveillance timeline or schedule recommendations.

Smolle et al conducted a systematic review of abdominal and retroperitoneal metastases in primary extremity soft tissue sarcoma. According to six included studies that reported directly on abdominal and retroperitoneal metastases, myxoid liposarcoma went to these locations 2-6 times more often than other extremity soft tissue sarcomas. Other sarcomas that did metastasize to these locations include leiomyosarcoma, epithelioid sarcoma, malignant peripheral nerve sheath tumors, and synovial sarcoma. They recommended abdominal/pelvic CT imaging surveillance for early detection of extrapulmonary metastases.

Figure A is the axial T1 weighted image showing a uniformly dark lesion isointense to muscle adjacent to the rectus femoris muscle. Figure B is the axial T2 weighted MRI showing a bright, heterogenous lesion in the anterior compartment consistent with a myxoid neoplasm. Figure C is the sagittal T2 weighted MRI showing the bright, heterogenous myxoid neoplasm in the anterior compartment.

Illustration A shows an axial CT of the abdomen showing metastatic liposarcoma to the retroperitoneum.

Incorrect Answers:
Answer 1: Full body PET-CT has not been shown to be superior to MRI of the involved extremity and CT chest/abdomen/pelvis
Answers 2 and 3: Chest radiographs and chest CT are routinely involved in pulmonary surveillance for extremity sarcomas, however, myxoid liposarcoma has been shown to metastasize abdominal and retroperitoneal locations, and chest only surveillance would miss detection of these locations.
Answer 5: Extremity ultrasound has not been shown to be superior to MRI, and chest CT is insufficient for proper surveillance of myxoid liposarcoma.