Imaging features and clinical course of undifferentiated round cell sarcomas with CIC-DUX4 and BCOR-CCNB3 translocations

Abstract

Objective: To describe the pre-treatment imaging features and clinical course of undifferentiated round cell sarcomas with CIC-DUX4 and BCOR-CCNB3 translocations.

Materials and methods: In this retrospective study, several pre-treatment imaging features (tumor location, size, enhancement pattern, necrosis, flow voids, calcification, and FDG avidity) and the clinical course of patients were evaluated.

Results: In 12 patients with CIC-DUX4 sarcomas (median age, 24 years; range, 12-75), sarcomas were located in the soft tissue (n = 10), bone (n = 1), and lungs (n = 1). On MRI, all 10 CIC-DUX4 sarcomas presented as a large necrotic mass (mean size 6.7 cm, range 2.3-11.3) with 100% demonstrating contrast enhancement, 60% showing flow voids, and 20% demonstrating fluid-fluid levels. On PET, the mean SUVmax was 13.2 (range, 8.5-18.1). Among 12 patients with follow-up, 3 died within a year of diagnosis. The most common site of metastases was the lungs (5/12). In 5 patients with BCOR-CCNB3 sarcomas (median age, 14 years; range, 2-17), sarcomas were located in the spine (n = 2), femur (n = 1), tibia (n = 1), and pelvis (n = 1). On radiograph or CT, 2 were lytic, 3 were sclerotic. Soft tissue calcifications occurred in 40% of BCOR-CCNB3 sarcomas. On MRI, all 3 BCOR-CCNB3 tumors enhanced with 33% demonstrating flow voids and 66% exhibiting necrosis. On PET, the mean SUVmax was 6.3 (range 5.7-6.9).

Conclusion: CIC-DUX4 sarcomas often present as necrotic and hypermetabolic soft tissue masses while sarcomas with BCOR-CCNB3 translocations are vascular bone lesions with necrosis at imaging. CIC-DUX4 sarcomas are clinically more aggressive than BCOR-CCNB3 sarcomas.

Keywords: BCOR-CCNB3; CIC-DUX4; CT; MRI; PET; Undifferentiated round cell sarcoma.

Fig. 1.

A 17-year-old man with a CIC-DUX4 tumor in the left gluteus maximus muscle. Coronal Short-TI Inversion Recovery (STIR) (a) and coronal T1-weighted fat-suppressed post-contrast (b) images show a tumor with a well-defined border and multiple linear and punctate flow voids (arrows) suggestive of vascularity. The tumor shows heterogenous contrast enhancement and necrosis (arrowheads). The tumor (T) demonstrates low attenuation on non-contrast CT (c) and is FDG-avid with SUVmax 11.1 on PET/CT (d).

Fig. 2.

A 12-year-old girl with a CIC-DUX4 tumor in her left 3^rd rib, mimicking an Askin tumor. Axial CT image (a) shows a rib lesion with a well-circumscribed soft tissue mass. Axial T1-weighted (b) and T2-weighted (c) images demonstrate medullary involvement by the tumor (arrows). Axial T1-weighted fat-suppressed post-contrast (d) image shows heterogenous contrast enhancement with necrosis (asterisk). Vascularity in the tumor is evidenced by low signal foci (arrowhead).

Fig. 3.

A 58-year-old woman with a CIC-DUX4 tumor in her left paraspinal musculature. Axial T1-weighted (a) and T2-weighted (b) images show an intramuscular tumor containing multiple fluid levels (arrows) and high T1 and T2 signal suggestive of hemorrhage. Axial T1-weighted fat-suppressed post-contrast image (c) shows peripheral and internal septal contrast enhancement (curved arrows) in the intramuscular tumor.

Fig. 4.

A 21-year-old woman with a CIC-DUX4 tumor in the anterior abdominal wall. Axial T2-weighted image (a) shows a subcutaneous mass containing multiple fluid levels (arrowheads) compressing on the muscles. Axial T1-weighted fat-suppressed post-contrast image (b) shows an enhancing posterior component (arrow). Axial fused PET-MRI image (c) shows FDG avidity with SUVmax measuring 5.1 in the solid component.

Fig. 5.

A 75-year-old woman with a CIC-DUX4 tumor in the right upper lobe with bilateral adrenal glands mimicking a primary lung cancer. Axial CT image (a) shows a well-defined right upper lobe mass. Axial fused PET-CT images (b, c) show that the mass and adrenal metastases are heterogeneously FDG avid with SUVmax measuring 18.1 in the lung mass, 9.3 in the right adrenal mass, and 7.1 in the left adrenal mass.

Fig. 6.

An 8-year-old boy with a BCOR-CCNB3 tumor in his right proximal femur. AP scout view of PET (a) shows a right femoral permeative lytic lesion (arrows) with cortical thickening (arrowhead). On an axial PET image (b), the lesion is lytic with cortical thinning (arrowheads) and periosteal reaction (curved arrow) with a soft tissue mass (T). On a PET MIP image (c), the lesion is hypermetabolic at the femoral metadiaphysis with an SUVmax of 5.7 within the soft tissue mass (arrowhead) and photopenic in the femoral diaphysis (arrow). On a coronal STIR image (d), the lesion is in the proximal femoral metadiaphysis and diaphysis (arrows) with a soft tissue mass (arrowhead). On an axial T1-weighted fat-suppressed post-contrast image (e), the tumor shows heterogenous contrast enhancement with non-enhancing areas (arrowheads) and the soft tissue mass (T) extends beyond the periosteum (arrows).

Fig. 7.

A 14 year-old-boy with a BCOR-CCNB3 tumor in left ilium. Axial CT image (a) shows a partially calcified left iliac mass (arrow) with a soft tissue mass (*) containing few small calcifications (arrowheads). Axial T1-weighted fat-suppressed post-contrast image (b) shows the enhancing intraosseous tumor (arrow) and soft tissue mass with a non-enhancing area suggestive of necrosis (*).