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DOI:10.2214/AJR.07.3415
AJR 2008; 190:1492-1494
© American Roentgen Ray Society

Technical Innovation

Radiofrequency Ablation of Solitary Eosinophilic Granuloma of Bone

Rodney R. Corby1, Gregory S. Stacy1, Terrance D. Peabody2 and Larry B. Dixon1

1 Department of Radiology, The University of Chicago Medical Center, MC 2026, 5841 S Maryland Ave., Chicago, IL 60637.
2 Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Medical Center, Chicago, IL.

Received November 12, 2007; accepted after revision December 21, 2007.

 
Address correspondence to R. R. Corby (rod_corby{at}yahoo.com).


Abstract
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 Abstract
Introduction
 Technique
 Results
 Discussion
 References
 
OBJECTIVE. This article about our initial clinical experience describes the novel application of radiofrequency ablation for the treatment of two cases of solitary eosinophilic granuloma of the bone.

CONCLUSION. Technical success was achieved in both cases with a prompt clinical response and no treatment-related complications. To our knowledge, this is the first description of the application of radiofrequency ablation for the treatment of solitary eosinophilic granuloma of the bone.

Keywords: bone • electrosurgical device • eosinophilic granuloma • radiofrequency ablation


Introduction
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 Abstract
 Introduction
Technique
 Results
 Discussion
 References
 
Eosinophilic granuloma (EG), the monosystemic osseous form of Langerhans cell histiocytosis, typically affects children in the first two decades of life. EG of bone may be mon- or polyostotic and most commonly involves the skull, mandible, and ribs in adults and the vertebrae and long bones in children [1, 2]. Although monostotic EG is considered a benign lesion, the time required for resolution is unpredictable and can be associated with significant morbidity secondary to unremitting pain, restricted activity, growth disturbance, or pathologic fracture [2].

Treatment options are disputed, and the often benign course and spontaneous healing of these lesions are well documented [2, 3]. Many proven and effective therapies exist including wide excision, curettage with or with out bone grafting, intralesional steroids, and local external beam radiation [2-4]. Surgical treatment often entails prolonged recovery and has significant associated morbidities. Advances in imaging-guided intervention offer new options for the treatment of EG of bone.

Radiofrequency ablation involves the application of energy in the radio wave frequency resulting in local thermal coagulative necrosis [5]. In 1992, Rosenthal et al. [6] first described the radiofrequency ablation of osteoid osteoma, for which radiofrequency ablation has become the standard treatment. Radiofrequency ablation has subsequently met success in both musculoskeletal and visceral applications. In this article about our initial clinical experience, we describe the application of radiofrequency ablation for the treatment of EG of bone as a minimally invasive treatment option.


Technique
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 Abstract
 Introduction
 Technique
Results
 Discussion
 References
 
Two patients were referred from our orthopaedic oncology clinic with symptomatic biopsy-proven EG of bone. Informed consent was obtained from the patients' parents. General anesthesia was necessary because of the potential for significant pain associated with radiofrequency ablation. Two grounding pads were applied to the patients' legs before the start of the procedure.

A 6-cm, 11-gauge StarBurst access system (RITA Medical Systems) (case 1) or a 10-cm, 11-gauge Osteo-Site bone biopsy needle (Cook Medical) (case 2) was advanced and buried in the cortex under CT guidance. A Bonopty extended drill (C. R. Bard) was then used to bore the cortex to the level of the lesion. A 10-cm (case 1) or 15-cm (case 2) StarBurst XL electrosurgical device (RITA Medical Systems) was then advanced into the center of the lesion under CT guidance and the tines unroofed to the maximum extent allowed by the confines of the cortex of the bone in an attempt to ablate as much of the lesion as possible.

An initial energy application using a RITA Model 1500x generator (RITA Medical Systems) was applied to achieve a temperature of 90°C for 6 minutes. After a cooldown period of 5 minutes, the electrosurgical device was retracted slightly within the lesion to ensure ablation of the portion of the lesion closest to the introducer. A second energy application was applied to achieve a temperature of 90°C for 3 minutes. This was an arbitrary decision based on the assumption that the majority of the lesion, if not the entire lesion, was completely treated during the first ablation. A dressing was applied and the patients were admitted for pain management. The patients were discharged the following day with appropriate analgesia. The orthopedic service instructed the patients to use crutches for 6 weeks and then to bear weight as tolerated by pain. These recommendations were made on the basis of the size of the lesion and involvement of weight-bearing bone.


Figure 1
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  		Fig. 1A —7-year-old girl with eosinophilic granuloma of proximal femur. Anteroposterior radiograph of femur shows proximal diaphyseal radiolucent lesion with surrounding thick periosteal reaction.

 


Figure 2
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  		Fig. 1B —7-year-old girl with eosinophilic granuloma of proximal femur. Axial CT image through target lesion shows electrosurgical device with tines unroofed centrally within lesion.

 


Figure 3
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  		Fig. 1C —7-year-old girl with eosinophilic granuloma of proximal femur. Anteroposterior radiograph of femur 12 months after intervention shows healing of lesion without complication.

 

Results
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 Introduction
 Technique
 Results
Discussion
 References
 
Case 1
A 7-year-old girl presented with a 2-month history of a limp and unremitting pain. Radiographs showed a lytic lesion in the right femoral diaphysis with surrounding chronic periosteal reaction (Fig. 1A). A subsequent CT-guided biopsy confirmed the diagnosis of EG. After a discussion of the treatment options, radiofrequency ablation was performed approximately 1 month after presentation (Fig. 1B). The procedure took a total of 60 minutes, and there were no complications. The patient experienced complete resolution of pain 7 days after therapy and returned to normal activity levels over the next several months. Subsequent radiographs 12 months after the intervention showed progressive healing of the lesion (Fig. 1C).

Case 2
A 14-year-old girl was referred from an outside institution, where she presented with left hip pain and underwent a failed (unable to locate the target lesion) open biopsy and curettage of a left supraacetabular lesion. Radiographs at our institution showed a lytic lesion in the left supraacetabular ilium (Fig. 2A), and a subsequent CT-guided biopsy confirmed the diagnosis of EG. After a discussion of the treatment options, the patient opted for minimally invasive radiofrequency ablation. The procedure was performed 2 weeks after presentation (Fig. 2B). The total procedure time was 90 minutes, and there were no complications. The patient experienced complete resolution of pain 2 days after the procedure and returned to normal activity levels over the next several months. Subsequent radiographs 11 months after the intervention showed progressive healing of the lesion (Fig. 2C).


Figure 4
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  		Fig. 2A —14-year-old girl with eosinophilic granuloma of left supraacetabular ileum. Anteroposterior radiograph of left pelvis shows radiolucent lesion of supraacetabular ileum with mild surrounding sclerosis.

 

Figure 5
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  		Fig. 2B —14-year-old girl with eosinophilic granuloma of left supraacetabular ileum. Axial CT image through target lesion shows electrosurgical device with tines unroofed centrally within lesion. Anterolateral to target lesion is surgical defect from prior failed open biopsy and curettage.

 

Figure 6
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  		Fig. 2C —14-year-old girl with eosinophilic granuloma of left supraacetabular ileum. Anteroposterior radiograph of left pelvis 11 months after intervention shows slight decrease in size and increased peripheral sclerosis consistent with partial healing.

 

Discussion
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 Abstract
 Introduction
 Technique
 Results
 Discussion
References
 
The primary objectives of treatment of monostotic EG are the relief of unremitting pain, a prompt return to normal activities, and the prevention of long-term complications, namely, pathologic fracture and growth plate disturbance. The current treatment of solitary EG is often concurrent with open biopsy and includes wide excision, curettage and bone grafting, intralesional steroids, or local external radiation [7]. Although proven effective, a surgical approach can be associated with prolonged recovery time, neurologic injury, postoperative fracture, and wound infection [7].

Advances in imaging-guided intervention offer diagnosis and therapy using a minimally invasive percutaneous approach. CT-guided radiofrequency ablation has become the standard of care for the management of osteoid osteoma. Radiofrequency ablation has been reported in the treatment of chondroblastoma, epithelioid hemangioma, chordoma, and metastatic disease [5]. In this article, we describe the novel application of radiofrequency ablation for the treatment of solitary EG of bone.

The decision to treat a lesion percutaneously often depends on the surgeon's preference for obtaining histologic confirmation [7]. In each case presented, a percutaneous CT-guided biopsy was performed for histologic confirmation. Unremitting pain and limitation of activity prompted therapy in both cases. Radiofrequency ablation was chosen with the objective of reducing recovery time and potential postoperative complications and achieving a superior cosmetic result. Additional influences in case 2 were the previous failed surgical attempt and the risks associated with disarticulating the hip with operative management.

Energy in the radiofrequency range applied to an electrode results in local tissue heating that can be used to ablate a controlled volume of tissue [5]. It has been shown that tissue heating to 47°C for 30 seconds causes thermal necrosis of bone [8]. The diameter of coagulation depends on the current, duration of treatment, and local tissue blood flow. The larger size of many EG lesions compared with osteoid osteoma necessitates a larger treatment volume. The Star-Burst XL electrosurgical device we used is an umbrella-type expanding electrode capable of providing treatment volumes up to 3 to 5 cm in diameter when fully unroofed. This allowed treatment with only a single access point. In larger lesions, more ablations may be necessary, possibly with multiple access points.

Radiofrequency ablation is not a suitable alternative for all patients. Treatment of any lesion within 1 cm of a critical neural or visceral (bladder or bowel) structure is contraindicated because of the potential for injury secondary to thermal diffusion. Excessively large lesions may be better suited to surgical therapy, especially in weight-bearing bones. Alternatively, the instillation of cement after radiofrequency ablation may be considered in larger lesions to reduce subsequent fracture risk. Finally, because EG has a variety of imaging appearances and hence may mimic other pathologic processes ranging from infection to malignancy, preablation histologic confirmation is necessary.

The mechanism by which radiofrequency ablation induces osseous remodeling is unknown, and it is unclear if the rate of healing was influenced by treatment in these cases. Previous reports have shown that the rate of resolution is unaffected by the mode of treatment [3]. Reported rates of postintervention healing vary widely, ranging from 3 to 24 months [3, 4, 7]. Our cases fall within this range. Although a definite therapeutic effect cannot be proven, the radiographic response and rapid pain relief support the efficacy of this treatment. We hope this report will generate further research of radiofrequency ablation for the treatment of EG of bone as a minimally invasive alternative to surgery.


References
Top
 Abstract
 Introduction
 Technique
 Results
 Discussion
 References
 

  1. Ghanem I, Tolo VT, D'Ambra P, Malogalowkin MH. Langerhans cell histiocytosis of bone in children and adolescents. J Pediatr Orthop 2003; 23:124 -130[CrossRef][Medline]
  2. Cohen M, Zornoza J, Cangir A, Murray JA, Wallace S. Direct injection of methylprednisolone sodium succinate in the treatment of solitary eosinophilic granuloma of bone: a report of 9 cases. Radiology 1980;136 : 289-293[Abstract/Free Full Text]
  3. Sartoris DJ, Parker BR. Histiocytosis X: rate and pattern of resolution of osseous lesions. Radiology1984; 152:679 -684[Abstract/Free Full Text]
  4. Boutsen Y, Esselinckx W, Delos M, Nisolle JF. Adult onset of multifocal eosinophilic granuloma of bone: a long-term follow-up with evaluation of various treatment options and spontaneous healing. Clin Rheumatol 1999;18 : 69-73[CrossRef][Medline]
  5. Rosenthal DI. Radiofrequency treatment. Orthop Clin North Am 2006; 37:475 -484[CrossRef][Medline]
  6. Rosenthal DI, Alexander A, Rosenberg AE, Springfield D. Ablation of osteoid osteomas with a percutaneously placed electrode: a new procedure. Radiology 1992;183 : 29-33[Abstract/Free Full Text]
  7. Greis PE, Hankin FM. Eosinophilic granuloma: the management of solitary bone lesions. Clin Orthop 1990;257 : 204-211[Medline]
  8. Lundskog J. Heat and bone tissue: an experimental investigation of the thermal properties of bone and threshold levels for thermal injury. Scand J Plast Reconstr Surg 1972;9 : 1-80[Medline]

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 Am. J. Roentgenol.Home page
P. L. Munk, D. Malfair, F. Rashid, and W. C. Torreggiani
Radiofrequency Ablation of Solitary Eosinophilic Granuloma of Bone
Am. J. Roentgenol., December 1, 2008; 191(6): W320 - W320.
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 Am. J. Roentgenol.Home page
R. R. Corby, G. S. Stacy, T. D. Peabody, and L. B. Dixon
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Am. J. Roentgenol., December 1, 2008; 191(6): W321 - W321.
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This Article
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