Indications for Magnetic Resonance Imaging Studies in Children with Multiple Hereditary Osteochondromas Who Are at Risk for Intraspinal Osteochondromas

Background: Multiple Hereditary Osteochondromas (MHO) is a hereditary skeletal disorder presenting in children, characterized by growths of benign osteochondral masses. The lifetime risk of malignant progression is low, but on rare occasions these lesions can grow on the axial skeleton and compress the spinal cord, leading to neurologic signs and symptoms, including radiculopathy, quadriparesis, and paresthesias. Due to the unclear indications for screening for these lesions, learning more about patient factors that are associated with the development of intracanal spinal osteochondromas will help to improve screening guidelines.

Methods: We reviewed the records of 183 patients who were queried by a diagnosis of MHO or exostosis. The study population comprised 61 pediatric patients (aged 0-17) who met our study criteria: diagnosed with MHO and completed spinal MRI screening between Jan 1, 2011, and Dec 31, 2019. Beginning in 2011, it has been our clinic protocol to screen from 8 years of age, as most children this age do not need to be sedated for the study. A complete medical chart and MRIs were reviewed. Information about the MHO progression and known skeletal osteochondromas were collected from the medical record. Characteristics of spinal lesions were collected from the initial MRI screening date. Poisson regression analyses were conducted to relate the collected patient characteristics to the number of intraspinal osteochondromas lesions. Missing values were handled by Multiple Imputation by Chained Equations.

Results: The mean age of MRI screening was 10 years old (2-15 years). Of the 61 study patients, 18 patients had intracanal osteochondromas and of these patients, 5 had neurological signs and or symptoms including myelopathy, 6 patients had back pain and all but one had at least one intracanal lesion. 6 of these 18 patients had at least one osteochondroma which required resection. The mean number of intracanal osteochondromas in patients with >10 total skeletal osteochondromas at the time of screening was 2.33 times greater (95% CI: 0.48 - 11.43, p=0.30) than those with < 10 osteochondromas, which though not significant, did trend positively. Age at screening MRI did correlate with the number of intracanal lesions identified, increasing 1.47 times for each year increment (95% CI: 1.07 - 2.02, p = 0.02), while adjusting for covariates.

Conclusion: A higher number of total osteochondromas, older age, and back pain appear to be measures of disease burden and risk factors for intracanal osteochondromas.