Korean J Radiol.  2017 Feb;18(1):94-106. 10.3348/kjr.2017.18.1.94.

Current Concepts in Non-Gastrointestinal Stromal Tumor Soft Tissue Sarcomas: A Primer for Radiologists

• Baheti AD
• Jagannathan JP
• O'Neill A
• Tirumani H
• Tirumani S

• KMID: 2468125
• DOI: http://doi.org/10.3348/kjr.2017.18.1.94

Abstract

Non-gastrointestinal stromal tumor (GIST) soft tissue sarcomas (STSs) are a heterogeneous group of neoplasms whose classification and management continues to evolve with better understanding of their biologic behavior. The 2013 World Health Organization (WHO) has revised their classification based on new immunohistochemical and cytogenetic data. In this article, we will provide a brief overview of the revised WHO classification of soft tissue tumors, discuss in detail the radiology and management of the two most common adult non-GIST STS, namely liposarcoma and leiomyosarcoma, and review some of the emerging histology-driven targeted therapies in non-GIST STS, focusing on the role of the radiologist.

Keyword

Soft tissue sarcomas; World Health Organization classification; Liposarcoma; Leiomyosarcoma

MeSH Terms

Humans
Leiomyosarcoma/classification/diagnostic imaging/genetics
Liposarcoma/classification/diagnostic imaging/genetics
Sarcoma/classification/*diagnostic imaging/genetics
Soft Tissue Neoplasms/classification/*diagnostic imaging/genetics
Tomography, X-Ray Computed
World Health Organization

Figure

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  Fig. 1 Sarcomagenesis and potential target pathways for molecular targeted therapy (indicated by strikethrough). PDGF = platelet-derived growth factor, VEGF = vascular endothelial growth factor

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  Fig. 2 61-year-old woman with well differentiated retroperitoneal liposarcoma. A. Axial contrast-enhanced CT image at time of diagnosis demonstrates large predominantly fat containing mass in left retroperitoneum (arrows). Presence of heterogeneous non-lipomatous component differentiates it from simple lipoma. B, C. Axial T1-out-of-phase and post-gadolinium fat-suppressed T1-weighted images demonstrate mass to have areas of signal drop on out-of-phase imaging with no significant enhancement (arrows). Patient underwent surgery and histopathology showed well-differentiated liposarcoma.

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  Fig. 3 50-year-old woman with dedifferentiated retroperitoneal liposarcoma. Axial contrast-enhanced CT images demonstrate large heterogeneous predominantly soft tissue containing mass in right retroperitoneum (arrows). Superior component of mass has fatty attenuation area (arrowheads) raising possibility of dedifferentiated retroperitoneal liposarcoma which was confirmed at histopathology.

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  Fig. 4 41-year-old man with myxoid liposarcoma. A. Axial T2-weighted image demonstrates homogeneously T2 hyperintense lesion mimicking cyst in anterior compartment of leg (arrow). B, C. Pre and post gadolinium fat-suppressed T1-weighted images demonstrate lesion to be T1 isointense with heterogeneous internal enhancement suggesting it to be solid mass (arrows). Patient underwent surgery and histopathology showed myxoid liposarcoma. T2 bright signal was due to myxoid component in tumor.

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  Fig. 5 61-year-old man with pleomorphic liposarcoma. A. Axial STIR image demonstrates large heterogeneously T2 hyperintense mass in anterior compartment of left thigh associated with marked surrounding T2 hyperintensity (arrows). B. Axial T1-weighted non-fat-suppressed image shows mass to be T1 isointense with no hyperintense areas to suggest macroscopic fat in mass (arrows). C. Post-gadolinium fat-suppressed T1-weighted images demonstrate heterogeneous enhancement of mass (arrows). Histopathology showed pleomorphic liposarcoma. STIR = short tau inversion recovery

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  Fig. 6 64-year-old woman with dedifferentiated retroperitoneal liposarcoma treated with trabectedin. A. Axial contrast-enhanced CT images before demonstrates large heterogeneous right perihepatic soft tissue mass (arrow). B. Follow-up CT 3 months after start of treatment shows decrease in density of mass with new fat attenuation component consistent with adipocytic maturation (arrow).

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  Fig. 7 60-year-old woman with leiomyosarcoma of deep soft tissues of extremity. A. Axial T2 non-fat-suppressed images demonstrates large well circumscribed solid cystic/necrotic T2 hyperintense mass in anterior compartment of right thigh. Note that peripheral T2 hyperintense component has low signal compared to subcutaneous fat (arrows). B, C. Pre and post gadolinium fat-suppressed T1-weighted images demonstrate thick rim of peripheral enhancement in mass (arrows). Histopathology confirmed leiomyosarcoma.

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  Fig. 8 81-year-old woman with retroperitoneal leiomyosarcoma. Axial contrast-enhanced CT images of abdomen demonstrate large heterogeneous mass in left lower retroperitoneum (arrows), confirmed to be leiomyosarcoma on pathology.

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  Fig. 9 58-year-old woman with inferior vena cava leiomyosarcoma. Axial contrast-enhanced CT images demonstrate large heterogeneous mass in right retroperitoneum (arrows). IVC is not separately seen below level of renal veins and displaced anteriorly above level of renal veins (arrowhead). Right kidney is compressed and displaced laterally. IVC = inferior vena cava

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  Fig. 10 72-year-old man with metastatic malignant PEComa treated with mTOR inhibitor. A, B. Axial contrast-enhanced CT image of abdomen demonstrate heterogeneous mass in right lobe of liver (arrows) consistent with biopsy proven metastasis from malignant PEComa. CT image of chest at same time shows clear lung bases. C, D. Follow-up CT after 3 months of treatment shows decrease in density of liver metastasis (arrows). Second lesion which was previously occult also shows decrease in density (arrowhead). Concurrent chest CT shows new peripheral subpleural patchy ground glass opacities in lung bases consistent with drug associated pneumonitis. mTOR = mechanistic target of rapamycin, PEComa = perivascular epithelioid cell tumors

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