CT-guided right proximal humeral bone cyst injection in a 3-year-old male
A healthy 3-year-old male with a history of right arm pain and limited range of motion presented after falling out of his bed. Radiographic imaging showed a right proximal humerus lesion with pathologic fracture (Figure 2a). The patient was referred to orthopedic surgery for further treatment. An initial period of 4 weeks was recommended to allow fracture healing. Despite an initial period of observation, the lesion did not resolve with successful fracture healing. To confirm the diagnosis an open biopsy was performed and showed hyalinized acellular cementum consistent with a UBC.
Treatment options were discussed and the family was amenable to a CT-guided doxycycline injection. A biopsy was performed confirming the presence of a benign UBC. Two consecutive doxycycline injections were then performed within 3 months.
Routine follow-up after the first doxycycline injection showed noticeable improvement in the patient’s discomfort and range of motion. The patient was cleared for normal activity due to decreased fracture risk as a result of intralesional ossification and increased cortical thickening. One month after the second injection, the patient was asymptomatic and had resumed normal activity with near normal range of motion. Repeat radiography at that time showed complete resolution of the UBC lesion with dense ossification and remodeling of the proximal humerus expansion (Figure 2b). The patient required occasional Tylenol following each procedure and no other complaints or complications were noted.
CT-guided left proximal humeral bone cyst injection in a 9-year-old male
A healthy 9-year-old male presented to the emergency room with atraumatic left shoulder pain. Radiographs demonstrated a lytic lesion of the left proximal humerus with visible septations and mild expansion of the cortical bone suggesting a UBC with a pathologic fracture (Figure 3).
Orthopedic review was not conclusive for UBC as a focal area of multiple septations was present on MRI suggesting the possibility of a secondary ABC, therefore an open biopsy was performed in the area of concern to establish a definitive diagnosis. The biopsy demonstrated fragments of membranous stroma with spindle cells, occasional giant cells, and focal recent hemorrhage and hemosiderin. Samples taken were negative for rearrangement of the USP6 (17p13.2) gene region, a gene strongly associated with ABC pathology thereby confirming the diagnosis of UBC.
Given these findings, the family elected to undergo CT-guided intralesional doxycycline injections after an initial period of 4 weeks of observation and weight bearing restriction to allow fracture healing, during which time the lesion did not resolve. An interventional radiology specialist conducted two rounds of doxycycline injections performed two months apart with the technique previously described. Serial radiographs demonstrated progressive resolution of the UBC with rapid ossification of the lesion, as well as decreasing expansion of the left proximal humerus (Figure 3b, c). The patient required occasional Tylenol following each procedure. No other complaints or complications were noted.
CT-guided left proximal humeral bone cyst injection in a 10-year-old male
A healthy 10-year-old male presented to the emergency department with a radiographically-diagnosed pathologic fracture of his left proximal humerus after playing flag football (Figure 4a). He was initially treated in a sling for 4 weeks and regained full ROM and strength upon successful fracture healing. Approximately 3 months after the original injury, the patient reported intermittent pain, and radiographs showed persistence of the UBC (Figure 4b). After discussion of treatment options, the parents elected for CT-guided intralesional doxycycline injections. The patient received 2 injections approximately 10 weeks apart. At a follow-up visit of 2 months after the second injection, the patient had normal use of his arm without pain and radiographs demonstrated increased consolidation of the UBC with increased cortical thickness. (Figure 4c). It was determined in the second procedure that there were minimal cystic portions of the lesion to inject in the future so he is currently being observed for recurrence. The injections were well-tolerated without complications apart from mild discomfort requiring Tylenol immediately post-procedure.
CT-guided right pelvis bone cyst injection in a 12-year-old female
A healthy 12-year-old female was evaluated in the emergency department for right hip pain after falling off of a trampoline. Initial imaging showed a UBC of the right ischium without evidence of pathological fracture (Figure 5a). The patient was ambulatory with a mild limp and improved with physical therapy until returning to the ED a few months later with the same complaint of right hip pain. Radiographs demonstrated size progression in the UBC necessitating treatment (Figure 5b). The patient was then referred to orthopedic surgery and after a discussion of treatment options, underwent serial doxycycline injections.
Three doxycycline injections were performed at 10-week intervals. The procedures were tolerated well with no complications or reported side effects. Remodeling and ossification of the UBC progressed over the course of three doxycycline injections (Figure 5c). The patient was symptom free after the first injection and was released to full activity after the second injection.
CT-guided right distal radius bone cyst injection in a 7-year-old female
A healthy 7-year-old female presented with a history of recurrent pathologic fractures of the right distal radius though a progressive UBC. Radiography revealed a expansile lytic lesion with a fallen fragment sign consistent with a pathologic fracture through a UBC (Figure 6a).
The fracture healed with nonoperative treatment in a splint for 4 weeks, but the bone remained expansile and the UBC failed to resolve. After discussion with the patient and family regarding potential treatment options, the family elected for treatment with CT-guided intralesional doxycycline injections which were performed 10 weeks apart. Radiographs taken after each injection demonstrated incremental cortical remodeling and ossification of the UBC lesion (Figure 6b, c). Follow up radiographs at 2 months and 9 months after the second injection, show increased ossification and cortical thickening (Figure 6c, d). She remained asymptomatic though her most recent follow-up, 10 months after the second injection. The patient and family denied any complications or treatment side effects apart from early mild post-procedural discomfort managed with Tylenol.