Atypically Located Osteoid Osteoma: Characteristics and Therapeutic Success After Image-Guided Thermal Ablation.

Purpose:  While ostoeid osteomas (OO) are typically located in long tubular bones, OO occurring elsewhere are referred to as "atypical". Aim of our study was to review the characteristics of atypically located OO, course of symptoms and therapy, as well as clinical outcome, safety, and patient satisfaction of radiofrequency ablation (RFA).
Materials and Methods:  In the period from 04/01 to 07/13, 33 patients were treated using thermal ablation (RFA or laser), partly with low temperature and short duration technique. Clinical records were analyzed. Additionally, 23 patients were interviewed via telephone. Primary endpoints were technical success, clinical success (recurrence rates), and adverse events. Secondary endpoints were course of symptoms and therapy as well as patient satisfaction.
Results:  Mean follow-up was 22.1 ± 21.5 months. Average patient age was 31.7 ± 16.3 years. Localization: Most atypical OO (61 %) were located in the lower extremity, followed by axial skeleton (26 %) and upper extremity (13 %). Pain anamnesis: 74 % of patients stated that their pain occured predominantly at night and responded to NSAID, as typical for OO. Diagnostics: Patients consulted on average 4 different doctors and in 52 % patients, ≥ 3 different radiologic imaging techniques where used before the diagnosis "OO" was made.
Outcome: Technical success of thermal ablation was 100 %. Primary clinical success was 91 %. Patient satisfaction was 100 %. No major complications occurred.
Conclusion:  In ¼ of cases, atypical OO did not show the typical pain characteristics of OO. Image-guided thermal ablation is a promising and safe therapy also for patients with atypical OO.
Key Points:   · Atypical OO are challenging regarding diagnostics and therapy. · Image-guided thermal ablation is a safe and effective procedure also for patients with atypical OO. · Image-guided thermal ablation shows high patient satisfaction.
Citation Format: · Seemann RJ, Märdian S, Schwabe P et al. Atypically Located Osteoid Osteoma: Characteristics and Therapeutic Success After Image-Guided Thermal Ablation. Fortschr Röntgenstr 2020; 192: 335 - 342.
Competing Interests: The authors declare that they have no conflict of interest.
(© Georg Thieme Verlag KG Stuttgart · New York.)