MRI analysis of simple and aneurysmal bone cysts in the proximal humerus: what actually matters in clinical routine

As simple as it sounds? The treatment of simple bone cysts in the proximal femur in children and adolescents: Retrospective multicenter EPOS study of 74 patients

Purpose

Simple bone cysts are among the most prevalent benign cystic tumor-like lesions in children. Proximal femoral simple bone cysts may require specific treatment because of increased fracture risk. With limited literature available on this specific localization, consensus regarding optimal treatment is lacking. We present a large international multicenter retrospective cohort study on proximal femoral simple bone cysts.

Methods

All consecutive pediatric patients with proximal femoral simple bone cyst from 10 tertiary referral centers for musculoskeletal oncology were included (2000-2021). Demographics, primary treatment, complications, and re-operations were evaluated. Primary outcomes were time until full weight-bearing and failure-free survival.

Results

Overall, 74 simple bone cyst patients were included (median age 9 years (range = 2-16), 56 (76%) male). Median follow-up was 2.9 years (range = 0.5-21). Index procedure was watchful waiting (n = 6), percutaneous procedure (n = 12), open procedure (n = 50), or osteosynthesis alone (n = 6). Median time until full weight-bearing was 8 weeks (95% confidence interval = 0.1-15.9) for watchful waiting, 9.5 (95% confidence interval = 3.7-15.3) for percutaneous procedure, 11 (95% confidence interval = -0.7 to 13.7) for open procedure, and 6.5 (95% confidence interval = 5.9-16.1) for osteosynthesis alone (p = 0.58). Failure rates were 33%, 58%, 29%, and 0%, respectively (p = 0.069). Overall failure-free survival at 1, 2, and 5 years was 77.8% (95% confidence interval = 68.2-87.4), 69.5% (95% confidence interval = 58.5-80.5), and 62.0% (95% confidence interval = 47.9-76.1), respectively.

Conclusion

A preferred treatment for proximal femoral simple bone cysts remains unclear, with comparable failure rates and times until full weight-bearing. Watchful waiting may be successful in certain cases. If not feasible, osteosynthesis alone can be considered. Treatment goals should be cyst control, minimizing complications and swift return to normal activities. Therefore, an individualized balance should be made between undertreatment, with potentially higher complication risks versus overtreatment, resulting in possible larger interventions and accompanying complications.

Level of evidence

Level IV, retrospective multicentre study.

The treatment of aneurysmal bone cysts

PURPOSE OF REVIEW

Aneurysmal bone cysts are rare, locally aggressive bone tumors. Optimal treatment of ABCs is still matter of debate as therapies including sclerotherapy, selective arterial embolization and systemic treatment with denosumab are increasingly utilized, in addition to or instead of traditional curettage. The purpose of this review is to discuss current concepts and difficulties in diagnosing and treating primary ABCs, based on latest available literature.

RECENT FINDINGS

In diagnostics, multiple new fusion partners of USP-6 have been described on next-generation sequencing specifically for primary ABCs. In a recent systematic review, failure rates of percutaneous injections and surgery were comparable. In a literature review, the use of denosumab seemed effective but resulted in multiple cases of severe hypercalcemia in children.

SUMMARY

Accurately diagnosing primary ABC is crucial for treatment decisions. Curettage remains a valid treatment option, especially with adjuvant burring, autogenous bone grafting and phenolization. Percutaneous sclerotherapy represents a solid alternative to surgery, with polidocanol showing good results in larger studies. Systematic therapy with denosumab exhibits favorable results but should be reserved in the pediatric population for unresectable lesions, as it may result in severe hypercalcemia in children. When selecting a treatment option, localization, stability and safety should be considered.

A 5-Year-Old Female With an Aneurysmal Bone Cyst of the Proximal Humerus

An aneurysmal bone cyst (ABC) is a non-malignant, skeletal tumor that is extremely rare and most commonly presents within the first two decades of life. Genetic mutation of the USP6 gene on chromosome 17 remains to be the most commonly accepted reasoning as ABC’s etiology remains unknown. As the radiographic appearance of ABC is quite similar to other kinds of bone cysts, a histological diagnosis is often required to attain a definitive diagnosis. Curettage remains the gold standard treatment with high chances of local recurrence. Evidence has shown the beneficial applications of administering a sclerosing agent. Further trials would improve the level of evidence available for physicians to make a better management plan. We have demonstrated the treatment of an aneurysm bone cyst of the proximal humerus on a 5-year-old female in this report, which might be utilized as a reference for future procedures.