Single dose intralesional doxycycline foam infusion promotes bone growth and resolution of an odontoid aneurysmal bone cyst

BACKGROUND: Aneurysmal bone cysts (ABCs) are locally invasive bone tumors that most commonly arise in long bone metaphyses, the vertebral column, and pelvis, often presenting in the second decade of life. ABCs can be treated with resection, radiation, arterial embolization, and intralesional curettage. More recently intralesional doxycycline foam injections, which appear to act through the inhibition of matrix metalloproteinases and angiogenesis, have been used successfully, although multiple treatments are often required with this approach. CASE DESCRIPTION: A 13-year-old male with an incidentally discovered ABC filling much of the odontoid process but not violating the native odontoid cortex was treated with a single intralesional doxycycline foam injection delivered through a transoral approach with an excellent radiographic result. After placing a Crowe-Davis retractor, a transoral exposure of the odontoid process was performed with neuronavigation guidance. A fluoroscopy-guided Jamshidi needle biopsy was performed and via the needle doxycycline foam (2 mL 50 mg/mL doxycycline, 2 mL 25% albumin, and 1 mL Isovue 370 mixed with 5 mL of air) was infused, filling the cystic cavities of the odontoid process. The patient tolerated the operation well. Two months postoperatively, a computed tomography (CT) scan demonstrated a decrease in the size of the lesion with substantial new bone formation. Repeat CT at 6 months showed no residual cystic lucency, formation of dense new bone, and only minimal irregularity of the cortex at the prior needle biopsy site. CONCLUSION: This case illustrates that the use of doxycycline foam can be an excellent option when managing ABCs that cannot be resected without incurring significant morbidity.