Peripheral and periosteal chondrosarcoma: MRI-pathological correlation in 58 cases

Area of Science:

• Oncology
• Radiology
• Orthopedic Surgery

Background:

• Peripheral/periosteal chondrosarcomas (PP-CS) are rare bone tumors.
• Distinguishing low-grade from high-grade PP-CS is crucial for treatment planning.
• Magnetic Resonance Imaging (MRI) is a key modality for evaluating bone tumors.

Purpose of the Study:

• To evaluate the efficacy of MRI in differentiating low-grade atypical cartilaginous tumor/grade 1 peripheral/periosteal chondrosarcoma (ACT/Gd1 PP-CS) from high-grade peripheral/periosteal chondrosarcoma (HG-PP-CS) and dedifferentiated peripheral/periosteal chondrosarcoma (DD-PP-CS).

Main Methods:

• Retrospective review of 58 patients with PP-CS diagnosed between 2007 and 2020.
• Histological grading of tumors into ACT/Gd1-PP-CS, HG-PP-CS, or DD-PP-CS.
• Independent review of MRI features by two musculoskeletal radiologists blinded to the final diagnosis.

Main Results:

• Periosteal tumors were 16 times more likely to be high-grade/dedifferentiated (HG/DD-CS) than peripheral tumors (p < 0.001).
• Intra-medullary tumor extension predicted HG/DD-CS (p = 0.004).
• Cap thickness (p = 0.04) and diffuse cap type (p = 0.03) differentiated low-grade from high-grade peripheral chondrosarcomas.

Conclusions:

• MRI features can effectively differentiate low-grade from high-grade peripheral/periosteal chondrosarcomas.
• Tumor origin (peripheral vs. periosteal) is a significant differentiating factor.
• Specific MRI findings like cap characteristics aid in grading peripheral chondrosarcomas.