Percutaneous Doxycycline Ablation for Recurrent Aneurysmal Bone Cyst in the Sacroiliac Joint: A Case Report.

Introduction: Aneurysmal bone cysts (ABCs) are benign, locally destructive, blood-filled reactive lesions of the bone most commonly presenting as pain or mass effect. Most are frequently located in the proximal humerus, distal femur, proximal tibia, spine, uncommonly the sacrum, and rarely the sacroiliac (SI) joint. We present a rare case of ABC in the SI joint and its recurrence treated with percutaneous intralesional doxycycline ablation and the corresponding outcome. Case Report: A 29-year-old female presented with persistent gluteal pain and radiculopathy and was subsequently diagnosed with ABC in the left SI joint. She underwent intralesional extended curettage with the application of synthetic bone graft substitute over the defect. One year postoperatively, local recurrence of the mass was noted after presenting with similar symptoms of radiculopathy. She then underwent six sessions of CT-guided percutaneous intralesional doxycycline ablation at 2-3-month intervals. Serial monitoring through plain CT scan showed interval development of intralesional osseous formation and decreased lytic spaces. At the latest follow-up of 3½ years after treatment cessation, the patient remained asymptomatic with no recurrence. Conclusion: This reports the only known local experience using non-invasive treatment for the recurrence of ABC in the SI joint through CT-guided intralesional ablation of doxycycline resulting in relief of symptoms and absence of recurrence at 3½ years post-treatment. This supports previous studies showing doxycycline administration as an effective alternative in the treatment of ABCs in recurrent cases, in challenging cases due to its location, or when located in non-expendable areas such as the SI joint and sacrum. More extensive studies with longer follow-ups are needed to validate these findings.