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Recurrence of a Unicameral Bone Cyst in the Proximal Part of the Fibula After en Bloc ResectionA Case Report
Richard E. Bowen, MD1; Raymond T. Morrissy, MD2
1 Shriners Hospitals For Children, Los Angeles Unit, 3160 Geneva Street, Los Angeles, Ca 90020. E-Mail Address: Rbowen@Shrinenet.Org
2 Children's Orthopaedics of Atlanta, 5445 Meridian Mark Road, Suite 250, Atlanta, GA 30342
View Disclosures and Other Information
The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.
Investigation performed at the Scottish Rite Children's Medical Center, Atlanta, Georgia

The Journal of Bone and Joint Surgery, Incorporated
J Bone Joint Surg Am, 2004 Jan 01;86(1):154-158
5 Recommendations (Recommend) | 3 Comments | Saved by 3 Users Save Case


The unicameral bone cyst is a relatively common lesion that usually is found at the time of a bone fracture during the first decade of life. These lesions exhibit a proclivity for the proximal part of the humerus, followed by the proximal part of the femur1.The natural history of the unicameral bone cyst is highly variable, and this complicates efforts to evaluate various treatment modalities. In addition, the unicameral bone cyst purportedly can transform into an aneurysmal bone cyst, a chondrosarcoma, or a Ewing sarcoma. This capacity of the unicameral bone cyst to change into other lesions further confuses the natural history2-4.
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    bone cysts ; fibula ; cyst

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    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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    Richard E Bowen
    Posted on May 10, 2004
    R.E. Bowen and R.T.Morrissy reply
    Shriners Hospitals for Children - Los Angeles

    To the Editor:

    We thank Dr. Leidinger for his comments regarding our article. Dr. Leidinger is correct that the periosteum was not removed at the time of resection of the simple cyst from the proximal fibula. We agree that a resection that does not include a cuff of normal tissue around the lesion does not meet the definition of a “wide” or “en bloc” resection. Such a resection has never, to our knowledge, been a recommended treatment for simple bone cyst. The purpose of the report was to demonstrate that with a subperiosteal en bloc resection of a simple cyst, recurrence was possible. This would seem to indicate that the factors responsible lie somewhere outside of the resected bone, possibly in the periosteum.

    It is possible that “tumor cells” mentioned by Dr. Leidinger could play a role. To our knowledge, however, no such cells have been identified. A thin layer of tissue containing flattened, mesothelial-like cells lines the inner surface of simple bone cysts. Their presence has not been described on the outer cortex of these lesions, and it is unclear what role if any these cells play any role in the development of the cyst. Without knowing the etiologic cells in the unicameral bone cyst, it is difficult to determine the margin of resection.

    We are grateful to Dr. Leidinger’s comments regarding our manuscript and hope that the further discussion clarifies the issues.

    Benedikt Leidinger
    Posted on April 15, 2004
    Recurrence After en Bloc Resection of Unicameral Bone Cyst
    University of Muenster, Department of orthopedics, Albert-Schweitzer-Str. 33, 48149 Muenster, German

    To the Editor:

    We read with interest the article, "Recurrence of a Unicameral Bone Cyst in the Proximal Part of the Fibula After en Bloc Resection. A Case Report." (2004; 86:154- 58), by Bowen et al(1). This interesting case again shows the anything but simple behaviour of bone cysts. Generally, recurrence after surgical treatment of UBC has been frequently (30-50%) reported regardless of the chosen therapy(2,3). Neither the suggested relationship of the periosteum nor any extrinsic factor or disordered endochondral ossification explains the recurrence of the cyst. Although the authors excised the proximal fibula with the fractured cyst, by leaving the periosteum intact the resection margin was not wide according to the criteria of Enneking(4). With an active UBC, this might be the reason for some tumor cell remnants in the periosteal tube.

    In active benign stage 3 lesions, recurrence is less likely only after wide en bloc resection but such an aggressive surgical treatment for a benign tumor-like-lesion with its associated morbidity is indicated only when other options have been tried, especially in an expendable bone like the fibula. Our recommendation is to first proceed with a minimally invasive procedure such as a steroid injection as the authors did with proven success.


    1. Bowen RE and Morrissy RT. Recurrence of a Unicameral Bone Cyst in the Proximal Part of the Fibula After en Bloc Resection. A Case Report. J Bone Joint Surg [Am] 2004;86:154-58.

    2. Enneking WF, Spanier SS, Goodman MA. A system for the surgical staging of musculoskeletal sarcoma. Clin Orthop. 1980;153:106-20.

    3. Inoue O, Ibaraki K, Shimabukuro H, Shingaki Y. Packing with high- porosity hydroxyapatite cubes alone for the treatment of simple bone cyst. Clin Orthop. 1993;293:287-92.

    4. Wilkins RM. Unicameral bone cysts. J Am Acad Orthop Surg 2000;8:217-24.

    Edward Gent
    Posted on February 05, 2004
    Recurrence of a Unicameral Bone Cyst
    Southampton General Hospital

    To the Editor:

    This interesting case report raises more questions than it answers. However

    It seems agreed that bone cysts originate at growth plates and can become distanced from the physis with growth. If latency is a true phenomenon in terms of response to treatment, then the periosteum can only have a secondary influence on cyst behaviour.

    The apparent centrifugal pattern of cyst development is also difficult to reconcile with periosteal induction. We have seen cyst-healing reverse completely in cysts some distance from the physis of origin but find this is unusual.

    Clearly bone cyst behaviour is anything but simple.

    1. Kaelin AJ,MacEwen GD. Unicameral bone cysts. Natural history and the risk of fracture. Int Orthop.1989;13:275-282.

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