From the Guidelines
Exostoses require regular surveillance with whole-body magnetic resonance imaging (WBMRI) starting at diagnosis, with a frequency of every 2-3 years, to monitor for potential malignant transformation into chondrosarcoma, which occurs in 0.2% to 5.9% of individuals 1.
Diagnosis and Surveillance
Exostoses are benign bony growths that develop on the surface of bones, most commonly in the metaphysis of long bones and the surface of flat bones. The diagnosis is typically made when at least two osteochondromas of the juxtaepiphyseal region of long bones and the surface of the flat bones are observed on radiological examination 1.
- The majority of cases are diagnosed between 3 and 5 years of age, and approximately 96% of cases develop osteochondromas before 12 years 1.
- Individuals may present with reports of pain, short stature, angular deformities of long bones, scoliosis, and leg length discrepancy 1.
Management
Treatment depends on the location and severity of symptoms.
- For asymptomatic exostoses, no intervention is necessary.
- When painful or causing complications, surgical removal may be recommended.
- Prevention includes using custom earplugs when swimming in cold water for ear exostoses, and comfortable shoes with adequate padding to reduce pressure and pain for foot exostoses.
Malignant Transformation
Malignant transformation into chondrosarcoma is a significant concern, with an incidence of 0.2% to 5.9% of individuals 1.
- Of those who develop chondrosarcoma, 75% are between 20 and 40 years of age, but earlier occurrences are reported 1.
- The incidence of transformation is higher in males and individuals with an EXT1 PV 1.
Imaging Modalities
WBMRI is the most valuable imaging modality in symptomatic exostoses, as it can precisely depict soft-tissue pathology and differentiate malignant transformation 1.
- A screening protocol for patients with multiple hereditary exostoses (MHE) includes lifelong biennial surveillance with WBMRI among other interventions 1.
From the Research
Definition and Prevalence of Exostoses
- Exostoses are slow-growing, benign bony outgrowths that are common clinical findings, often not causing concern for patients 2.
- However, they can lead to issues such as pressure, food abrasion, ulceration, or limited tongue space when removable prosthetics are used adjacent to or over these areas 2.
Surgical Techniques for Exostosis Removal
- Various surgical techniques have been developed for the removal of exostoses, including the use of a device as an alternative to a scalpel, offering a safe and predictable outcome 2.
- A transcanal micro-osteotome only technique has been used for excision of exostoses, without a postauricular incision or the use of a drill, with low complication rates and expeditious healing 3.
- Endoscopic ear surgery techniques have been compared to microscopic techniques for canalplasty procedures, showing significantly fewer minor postoperative complications with the endoscopic approach 4.
Surgical Outcomes and Complications
- Surgical resection of dorsal exostosis deformity of the metatarsocuneiform joints has been shown to be an effective procedure, with significant decreases in pain ratings and resolution of symptoms in most patients 5.
- However, complications such as neuritis, regrowth of the dorsal exostosis deformity, abscess formation, and pain at the Lisfranc joint have been reported 5.
- Complete excision of spinal exostoses has resulted in resolution of preoperative symptoms, while intralesional excision has led to recurrence in all cases 6.