Thin Cartilage Cap May Be Related to the Spontaneous Regression in Pediatric Patients with Osteochondroma

Background: The spontaneous regression of osteochondromas is rare, and only a few cases have been reported. Furthermore, the precise mechanism underlying spontaneous regression is unknown. This study aimed to examine the radiological findings of osteochondromas that had spontaneous regression and to identify potential indicators of this uncommon phenomenon in skeletally immature patients with osteochondromas. Methods: We included 28 patients (15 males and 13 females) who met the eligibility criteria between 2002 and 2019. The mean age at initial diagnosis was 9.7 years old (2-16 years). The mean follow-up period was 6.4 years (3-16 years). Results: Of the 28 patients, 10 (35.7%) had osteochondroma resolution. The osteochondroma resolved in one patient and regressed in nine. Tumor shrinkage is related to the thickness of the cartilage cap. The thickness of the cartilage cap did not correlate with age. Conclusions: Tumor shrinkage is associated with a thinner cartilage cap on magnetic resonance imaging. The thickness of the cartilage cap may be an important predictor of spontaneous regression in pediatric patients with osteochondroma.