Figure 1
Radiograph of the pelvis
AP digital radiograph of the pelvis reveals increased density of the left iliac bone (arrow) adjacent to the sacroiliac joint.
Unusual cause of low back pain: Osteosarcoma of the iliac bone
SectionMusculoskeletal system
Case TypeClinical Case
Authors
Antoine Vandendriessche 1,2, Filip Vanhoenacker 2,3,4
Connected authors
29 years, male
Clinical History
A 29-year-old man presents at the radiology department complaining of low back pain since 4 months, not radiating to the leg. There was no history of trauma.
Imaging Findings
Digital radiography revealed increased density of the left iliac wing (Figure 1).
Computer Tomography (CT) was performed in the same week of the radiograph, confirming sclerosis of the left iliac bone. A sunburst periosteal reaction and osteoid matrix formation in the adjacent soft tissue were seen with extension into the sacroiliac joint (SIJ) (Figure 2).
On Magnetic Resonance Imaging (MRI), the bone marrow of the left ileum was hypo-intense on T1- and T2-weighted images (WI). A large heterogeneous soft tissue component was seen on fat-suppressed (FS) T2-WI, FS T1-WI and T1-WI without FS. Diffusion-weighted imaging (DWI) showed diffusion restriction at the periphery of the lesion. After administration of gadolinium contrast, there was enhancement of the non-mineralised component. Transarticular involvement of the SIJ was seen (Figures 3a, 3b, 3c, 3d and 3e). Neo-adjuvant chemotherapy was started, followed by surgical hemi-pelvectomy and partial resection of the sacrum.
Histopathology confirmed the imaging diagnosis of osteosarcoma.
Discussion
Osteosarcoma (OS) is the most common primary bone tumour in adolescents, with a slight male predominance. Osteoid matrix formation is characteristic. OS typically occurs in the metaphysis of the long bones, with the knee being the most frequent localisation. Epiphyseal extension and joint involvement are common [1].
Primary involvement of the iliac bone is less common. Tumours located next to the SIJ need a precise evaluation with respect to their relationship to the joint, as this has a significant implication on surgical management. As a general rule, the synovial part of the joint constitutes a barrier, and extension will preferably occur through the ligamentous part of the joint [2]. However, aggressive tumours such as OS will occasionally extend through the synovium.
Non-specific pain and local swelling are usually the first signs of OS. Pathological fractures may also occur.
Radiography is the initial imaging modality of choice. Usually, the osteoid matrix production is sufficient to result in a cloudy moth-eaten area of increased density. Cortical destruction, with often extension into the soft tissues and aggressive periosteal reactions such as Codman triangle, onion skin and sunburst, is readily seen in long bones on radiographs but is far less evident in areas with a complex anatomy and superimposition such as the axial skeleton [1]. CT may play an additional role in detection and characterisation on these locations.
MRI is pivotal in local staging, evaluation of soft tissue extension and articular involvement. T1-WI is the most accurate sequence for the evaluation of tumour extension, which is often overestimated on T2-WI [3]. The osteoid matrix is of low signal on both T1- and T2-WI. DWI complements conventional T1- and T2-weighted imaging by early detection, adequate assessment of tumour extension and follow-up after therapy. Solid components enhance after administration of gadolinium contrast.
Histopathology is required for the final diagnosis. Different histological subtypes are identified depending on the dominant matrix. Sometimes the osteoid matrix is very subtle or cannot be seen macroscopically, which can make differential diagnosis very difficult [2,4].
The differential diagnosis with Ewing sarcoma is important, as it is more common in the pelvis than osteosarcoma. Ewing sarcoma usually presents with a larger soft tissue component and lacks osteoid matrix, although reactive bone formation is possible, which can make histological differentiation challenging [4].
Treatment consists of surgical resection and chemotherapy. Neo-adjuvant therapy is initiated for tumour volume reduction prior to surgery if limb-sparing approach is feasible [3].
Written informed patient consent for publication has been obtained.
Differential Diagnosis List
Osteosarcoma
Ewing sarcoma
Chondrosarcoma
Metastasis
Final Diagnosis
Osteosarcoma
References
[1] Zwaga T, Bovée JV, Kroon HM (2008) Osteosarcoma of the femur with skip, lymph node, and lung metastases. Radiographics 28(1):277-83. doi: 10.1148/rg.281075015. (PMID: 18203943)
[2] Chhaya S, White LM, Kandel R, Wunder JS, Ferguson P, Agur A (2005) Transarticular invasion of bone tumours across the sacroiliac joint. Skeletal Radiol 34(12):771-7. doi: 10.1007/s00256-005-0016-x. (PMID: 16184397)
[3] Clayer M (2015) Many faces of osteosarcoma on plain radiographs. ANZ J Surg 85(1-2):22-6. doi: 10.1111/ans.12836. (PMID: 25169836)
[4] Murphey MD, Robbin MR, McRae GA, Flemming DJ, Temple HT, Kransdorf MJ (1997) The many faces of osteosarcoma. Radiographics 17(5):1205-31. doi: 10.1148/radiographics.17.5.9308111. (PMID: 9308111)
Case information
| URL: | https://eurorad.org/case/18589 |
| DOI: | 10.35100/eurorad/case.18589 |
| ISSN: | 1563-4086 |
License
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Figure 2
CT of the pelvis
Axial CT image of the pelvis in bone window. Notice extensive sclerosis of the left iliac bone with sunburst periosteal reaction at the inner wall of the iliac wing (red arrow). There is osteoid matrix in the paraspinal and gluteus muscles (white arrows) with extension in the left sacroiliac joint (SIJ) through both the synovial part (orange arrow) and ligamentous part (blue arrow) of the joint.
Figure 3
MRI of the pelvis
Axial MRI images reveal a large mass in the left iliac bone extending into the surrounding soft tissues. The soft tissue mass is slightly heterogeneous on fat-suppressed (FS) T1-WI (Figure 3a) as well as on T1-WI without FS (Figure 3b) and even more heterogeneous on FS T2-WI (Figure 3c). The intra-osseous and soft tissue osteoid matrix is hypo-intense on T1- and T2-WI (Figures 3a, 3b and 3c). Slight diffusion restriction of the soft tissue component is seen on B800 diffusion-weighted images (DWI) with marked linear peripheral restriction (white arrows), demonstrating the tumour extension (Figure 3d). After administration of gadolinium contrast, there is enhancement of the non-mineralised component of the mass (Figure 3e). Extension of the tumour is seen through both the ligamentous (orange arrow) and synovial part (white arrow) of the SIJ (Figures 3a, 3b, 3c and 3e) with invasion of the sacral bone, being of hyper-intense signal on T2-WI (Figure 3c, red arrow) and slightly enhancing (Figure 3e, red arrow). Invasion of the sacrum is also seen on the DWI (Figure 3d, red arrow).
Axial MRI images reveal a large mass in the left iliac bone extending into the surrounding soft tissues. The soft tissue mass is slightly heterogeneous on fat-suppressed (FS) T1-WI (Figure 3a) as well as on T1-WI without FS (Figure 3b) and even more heterogeneous on FS T2-WI (Figure 3c). The intra-osseous and soft tissue osteoid matrix is hypo-intense on T1- and T2-WI (Figures 3a, 3b and 3c). Slight diffusion restriction of the soft tissue component is seen on B800 diffusion-weighted images (DWI) with marked linear peripheral restriction (white arrows), demonstrating the tumour extension (Figure 3d). After administration of gadolinium contrast, there is enhancement of the non-mineralised component of the mass (Figure 3e). Extension of the tumour is seen through both the ligamentous (orange arrow) and synovial part (white arrow) of the SIJ (Figures 3a, 3b, 3c and 3e) with invasion of the sacral bone, being of hyper-intense signal on T2-WI (Figure 3c, red arrow) and slightly enhancing (Figure 3e, red arrow). Invasion of the sacrum is also seen on the DWI (Figure 3d, red arrow).
Axial MRI images reveal a large mass in the left iliac bone extending into the surrounding soft tissues. The soft tissue mass is slightly heterogeneous on fat-suppressed (FS) T1-WI (Figure 3a) as well as on T1-WI without FS (Figure 3b) and even more heterogeneous on FS T2-WI (Figure 3c). The intra-osseous and soft tissue osteoid matrix is hypo-intense on T1- and T2-WI (Figures 3a, 3b and 3c). Slight diffusion restriction of the soft tissue component is seen on B800 diffusion-weighted images (DWI) with marked linear peripheral restriction (white arrows), demonstrating the tumour extension (Figure 3d). After administration of gadolinium contrast, there is enhancement of the non-mineralised component of the mass (Figure 3e). Extension of the tumour is seen through both the ligamentous (orange arrow) and synovial part (white arrow) of the SIJ (Figures 3a, 3b, 3c and 3e) with invasion of the sacral bone, being of hyper-intense signal on T2-WI (Figure 3c, red arrow) and slightly enhancing (Figure 3e, red arrow). Invasion of the sacrum is also seen on the DWI (Figure 3d, red arrow).
Axial MRI images reveal a large mass in the left iliac bone extending into the surrounding soft tissues. The soft tissue mass is slightly heterogeneous on fat-suppressed (FS) T1-WI (Figure 3a) as well as on T1-WI without FS (Figure 3b) and even more heterogeneous on FS T2-WI (Figure 3c). The intra-osseous and soft tissue osteoid matrix is hypo-intense on T1- and T2-WI (Figures 3a, 3b and 3c). Slight diffusion restriction of the soft tissue component is seen on B800 diffusion-weighted images (DWI) with marked linear peripheral restriction (white arrows), demonstrating the tumour extension (Figure 3d). After administration of gadolinium contrast, there is enhancement of the non-mineralised component of the mass (Figure 3e). Extension of the tumour is seen through both the ligamentous (orange arrow) and synovial part (white arrow) of the SIJ (Figures 3a, 3b, 3c and 3e) with invasion of the sacral bone, being of hyper-intense signal on T2-WI (Figure 3c, red arrow) and slightly enhancing (Figure 3e, red arrow). Invasion of the sacrum is also seen on the DWI (Figure 3d, red arrow).
Axial MRI images reveal a large mass in the left iliac bone extending into the surrounding soft tissues. The soft tissue mass is slightly heterogeneous on fat-suppressed (FS) T1-WI (Figure 3a) as well as on T1-WI without FS (Figure 3b) and even more heterogeneous on FS T2-WI (Figure 3c). The intra-osseous and soft tissue osteoid matrix is hypo-intense on T1- and T2-WI (Figures 3a, 3b and 3c). Slight diffusion restriction of the soft tissue component is seen on B800 diffusion-weighted images (DWI) with marked linear peripheral restriction (white arrows), demonstrating the tumour extension (Figure 3d). After administration of gadolinium contrast, there is enhancement of the non-mineralised component of the mass (Figure 3e). Extension of the tumour is seen through both the ligamentous (orange arrow) and synovial part (white arrow) of the SIJ (Figures 3a, 3b, 3c and 3e) with invasion of the sacral bone, being of hyper-intense signal on T2-WI (Figure 3c, red arrow) and slightly enhancing (Figure 3e, red arrow). Invasion of the sacrum is also seen on the DWI (Figure 3d, red arrow).
Radiograph of the pelvis
AP digital radiograph of the pelvis reveals increased density of the left iliac bone (arrow) adjacent to the sacroiliac joint.
© Department of Radiology, UZ Antwerpen, Edegem, Belgium, 2023
© Department of Radiology, UZ Antwerpen, Edegem, Belgium, 2023
CT of the pelvis
Axial CT image of the pelvis in bone window. Notice extensive sclerosis of the left iliac bone with sunburst periosteal reaction at the inner wall of the iliac wing (red arrow). There is osteoid matrix in the paraspinal and gluteus muscles (white arrows) with extension in the left sacroiliac joint (SIJ) through both the synovial part (orange arrow) and ligamentous part (blue arrow) of the joint.
© Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium, 2023
© Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium, 2023
MRI of the pelvis
Axial MRI images reveal a large mass in the left iliac bone extending into the surrounding soft tissues. The soft tissue mass is slightly heterogeneous on fat-suppressed (FS) T1-WI (Figure 3a) as well as on T1-WI without FS (Figure 3b) and even more heterogeneous on FS T2-WI (Figure 3c). The intra-osseous and soft tissue osteoid matrix is hypo-intense on T1- and T2-WI (Figures 3a, 3b and 3c). Slight diffusion restriction of the soft tissue component is seen on B800 diffusion-weighted images (DWI) with marked linear peripheral restriction (white arrows), demonstrating the tumour extension (Figure 3d). After administration of gadolinium contrast, there is enhancement of the non-mineralised component of the mass (Figure 3e). Extension of the tumour is seen through both the ligamentous (orange arrow) and synovial part (white arrow) of the SIJ (Figures 3a, 3b, 3c and 3e) with invasion of the sacral bone, being of hyper-intense signal on T2-WI (Figure 3c, red arrow) and slightly enhancing (Figure 3e, red arrow). Invasion of the sacrum is also seen on the DWI (Figure 3d, red arrow).
© Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium, 2023
© Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium, 2023
Axial MRI images reveal a large mass in the left iliac bone extending into the surrounding soft tissues. The soft tissue mass is slightly heterogeneous on fat-suppressed (FS) T1-WI (Figure 3a) as well as on T1-WI without FS (Figure 3b) and even more heterogeneous on FS T2-WI (Figure 3c). The intra-osseous and soft tissue osteoid matrix is hypo-intense on T1- and T2-WI (Figures 3a, 3b and 3c). Slight diffusion restriction of the soft tissue component is seen on B800 diffusion-weighted images (DWI) with marked linear peripheral restriction (white arrows), demonstrating the tumour extension (Figure 3d). After administration of gadolinium contrast, there is enhancement of the non-mineralised component of the mass (Figure 3e). Extension of the tumour is seen through both the ligamentous (orange arrow) and synovial part (white arrow) of the SIJ (Figures 3a, 3b, 3c and 3e) with invasion of the sacral bone, being of hyper-intense signal on T2-WI (Figure 3c, red arrow) and slightly enhancing (Figure 3e, red arrow). Invasion of the sacrum is also seen on the DWI (Figure 3d, red arrow).
© Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium, 2023
© Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium, 2023
Axial MRI images reveal a large mass in the left iliac bone extending into the surrounding soft tissues. The soft tissue mass is slightly heterogeneous on fat-suppressed (FS) T1-WI (Figure 3a) as well as on T1-WI without FS (Figure 3b) and even more heterogeneous on FS T2-WI (Figure 3c). The intra-osseous and soft tissue osteoid matrix is hypo-intense on T1- and T2-WI (Figures 3a, 3b and 3c). Slight diffusion restriction of the soft tissue component is seen on B800 diffusion-weighted images (DWI) with marked linear peripheral restriction (white arrows), demonstrating the tumour extension (Figure 3d). After administration of gadolinium contrast, there is enhancement of the non-mineralised component of the mass (Figure 3e). Extension of the tumour is seen through both the ligamentous (orange arrow) and synovial part (white arrow) of the SIJ (Figures 3a, 3b, 3c and 3e) with invasion of the sacral bone, being of hyper-intense signal on T2-WI (Figure 3c, red arrow) and slightly enhancing (Figure 3e, red arrow). Invasion of the sacrum is also seen on the DWI (Figure 3d, red arrow).
© Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium, 2023
© Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium, 2023
Axial MRI images reveal a large mass in the left iliac bone extending into the surrounding soft tissues. The soft tissue mass is slightly heterogeneous on fat-suppressed (FS) T1-WI (Figure 3a) as well as on T1-WI without FS (Figure 3b) and even more heterogeneous on FS T2-WI (Figure 3c). The intra-osseous and soft tissue osteoid matrix is hypo-intense on T1- and T2-WI (Figures 3a, 3b and 3c). Slight diffusion restriction of the soft tissue component is seen on B800 diffusion-weighted images (DWI) with marked linear peripheral restriction (white arrows), demonstrating the tumour extension (Figure 3d). After administration of gadolinium contrast, there is enhancement of the non-mineralised component of the mass (Figure 3e). Extension of the tumour is seen through both the ligamentous (orange arrow) and synovial part (white arrow) of the SIJ (Figures 3a, 3b, 3c and 3e) with invasion of the sacral bone, being of hyper-intense signal on T2-WI (Figure 3c, red arrow) and slightly enhancing (Figure 3e, red arrow). Invasion of the sacrum is also seen on the DWI (Figure 3d, red arrow).
© Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium, 2023
© Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium, 2023
Axial MRI images reveal a large mass in the left iliac bone extending into the surrounding soft tissues. The soft tissue mass is slightly heterogeneous on fat-suppressed (FS) T1-WI (Figure 3a) as well as on T1-WI without FS (Figure 3b) and even more heterogeneous on FS T2-WI (Figure 3c). The intra-osseous and soft tissue osteoid matrix is hypo-intense on T1- and T2-WI (Figures 3a, 3b and 3c). Slight diffusion restriction of the soft tissue component is seen on B800 diffusion-weighted images (DWI) with marked linear peripheral restriction (white arrows), demonstrating the tumour extension (Figure 3d). After administration of gadolinium contrast, there is enhancement of the non-mineralised component of the mass (Figure 3e). Extension of the tumour is seen through both the ligamentous (orange arrow) and synovial part (white arrow) of the SIJ (Figures 3a, 3b, 3c and 3e) with invasion of the sacral bone, being of hyper-intense signal on T2-WI (Figure 3c, red arrow) and slightly enhancing (Figure 3e, red arrow). Invasion of the sacrum is also seen on the DWI (Figure 3d, red arrow).
© Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium, 2023
© Department of Radiology, AZ Sint-Maarten, Mechelen, Belgium, 2023