Diagnostic discordance between MRI and histology in suspected malignant transformation of osteochondromas: a retrospective review

Abstract

Background: Accurately identifying malignant transformation in osteochondromas remains a clinical challenge, particularly due to variability in cartilage cap thickness measurements on magnetic resonance imaging (MRI). This study evaluates the concordance between MRI findings as reported by radiologists and histological diagnosis of surgically resected osteochondromas.

Methods: A single-centre retrospective cohort study was conducted on patients diagnosed with an osteochondroma from January 2016 to June 2024. Patients were diagnosed with an osteochondroma based on plain film radiographs (X-rays). MRI scan results were reviewed, as reported by experienced radiologists from an academic radiology department. Histological reports from all surgically excised osteochondromas were reviewed and compared to preoperative MRI reports.

Results: Forty-two patients with radiologically confirmed osteochondroma were reviewed. Twenty-four patients underwent MRI investigation and subsequent surgical resection for potential malignant transformation. Radiology reports suggested potential malignant transformation in 11 patients (46%), but only one case (4%) had histologically confirmed malignant transformation. The discordance between MRI and histology was statistically significant (p = 0.002), indicating MRI overestimation.

Conclusion: MRI appears to overestimate malignant transformation in osteochondromas, with poor correlation to histology. We speculate that this discordance is due to inaccuracies in measuring the thickness of the cartilage cap during radiological (MRI) evaluation.

Level of evidence: 4