Pathological fracture due to the aneurysmal bone cyst involving a large segment of radius diaphysis in an adolescent: A case report and 5-year follow-up

Ganesh Singh Dharmshaktu; Ishwar Singh Dharmshaktu; Naveen Agarwal

doi:10.4103/juoa.juoa_3_22

CASE REPORT

Year : 2022 | Volume : 1 | Issue : 1 | Page : 29-31

Pathological fracture due to the aneurysmal bone cyst involving a large segment of radius diaphysis in an adolescent: A case report and 5-year follow-up

Ganesh Singh Dharmshaktu, Ishwar Singh Dharmshaktu, Naveen Agarwal
Department of Orthopaedics, Government Medical College, Haldwani, Uttarakhand, India

Date of Submission	15-Mar-2022
Date of Acceptance	06-Jul-2022
Date of Web Publication	23-Jan-2023

Correspondence Address:
Ganesh Singh Dharmshaktu
Department of Orthopaedics, Government Medical College, Haldwani - 263 139, Uttarakhand
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/juoa.juoa_3_22

Abstract

A cystic lesion of the long bones occasionally presents with a pathological fracture. Various etiologies are described, and the aneurysmal bone cyst (ABC) is an uncommon lesion in the forearm bones. Usually, ABC involves the metaphyseal region as an eccentric expansile lesion and its presence in diaphysis is rare. Involvement of a large segment of a long bone is a very uncommon presentation for any cystic lesion including ABC. Fracture resulting in the settings of ABC with an extensive diaphyseal involvement is a rare and challenging presentation. We describe relevant details pertaining to a case of a 13-year-old female involving a large segment of the radial diaphysis that was managed operatively and finally diagnosed as ABC. She had good outcome in the follow-up of 5 years, and no postoperative complication or recurrence was noted.

Keywords: Aneurysmal bone cyst, benign lesion, forearm bone, pathological fracture, radius diaphysis

How to cite this article:
Dharmshaktu GS, Dharmshaktu IS, Agarwal N. Pathological fracture due to the aneurysmal bone cyst involving a large segment of radius diaphysis in an adolescent: A case report and 5-year follow-up. J Uttaranchal Orthop Assoc 2022;1:29-31

How to cite this URL:
Dharmshaktu GS, Dharmshaktu IS, Agarwal N. Pathological fracture due to the aneurysmal bone cyst involving a large segment of radius diaphysis in an adolescent: A case report and 5-year follow-up. J Uttaranchal Orthop Assoc [serial online] 2022 [cited 2023 Jun 3];1:29-31. Available from: http://www.juoa.org/text.asp?2022/1/1/29/368388

Introduction

Cystic lesions involving the long bones usually present with pathological fracture despite their commonly dormant behavior. Aneurysmal bone cyst (ABC) is uncommon (0.14 per 100,000 of the population per year) than the most common cystic lesion of the bone called unicameral bone cyst (UBC) or simple bone cyst and has varying described presentations.^[1] Long bones are followed by the spine and pelvis in the frequency of involvement.^[2] ABC is further uncommon in the diaphyseal region as its location is mostly reported in the metaphyseal region as an expansile lesion. Younger age of involvement with the medullary region of metaphysis is a common characteristic of ABC, but rarely, these may originate from the cortical or superficial region of diaphysis. Only 10 cases (out of 84) in a large series of ABC were found in diaphysis, thus highlighting its rarity.^[3] The diaphyseal lesions, however, were found more prone to pathological fracture than metaphyseal ones and the most necessitate operative interventions. One rare variety of ABC called solid-variant ABC has been described with aggressive eccentric lesion in diaphysis of long bones with distinct clinicoradiologic features.^[4] Involvement of a long segment of the bone with little cortical expansion is a deviant presentation of ABC that may occasionally come to notice along with pathological fracture.

Case Report

A 13-year-old female patient presented to us with pain and swelling in her left forearm after lifting heavy object in the kitchen. She thought of it as simple muscle ache and took fomentation and pain medication at home and only consulted when pain was unbearable on even slightest forearm movement, and she could not use her left upper limb properly. On clinical examination, swelling, pain, and crepitations were noted in the mid-forearm region but without local increased temperature, adjacent joint involvement, or distal neuromuscular deficit. The radiographs of the affected forearm revealed fracture of the middle third diaphysis of radius. The bony anatomy of the radius in the region adjacent to the fracture and extending to a large diaphyseal segment seemed abnormal on radiographs [Figure 1]. The bone with endosteal thinning of cortices across the involved segment appeared as consisting of multiple lesions. Suspecting an underlying bone pathology, magnetic resonance imaging (MRI) was performed which confirmed the presence of pathological bony changes on either side of the fracture involving a large segment of diaphysis [Figure 2]a and [Figure 2]b. The presence of multiloculated cystic lesion with thinning of endosteal surfaces along the lesion was also noted. There were multiple areas showing fluid-fluid level within the lesion as well [Figure 2]c and [Figure 2]d. A differential diagnosis of a benign cystic lesion-like simple bone cyst or ABC was suggested subjecting the final diagnosis to histopathological correlation. Fracture fixation and simultaneous biopsy were planned, and the fracture was fixed with one titanium elastic nail following the collection of few bony and soft tissue samples adjacent to fracture site [Figure 3]a. An above elbow protection plaster slab was also provided after completion of procedure. The plaster was removed after 6 weeks, and the active range of motion exercise of elbow, wrist, and fingers was encouraged throughout the whole course of treatment. The postoperative period and entire follow-up were uneventful with no localized or systemic complications noted. The biopsy was consistent with the diagnosis of ABC with no atypia, necrosis, or mitotic activity. The fracture went into a slow but gradual union, and radiographs on the final follow-up after 5 years showed complete union of the fracture and healing of the underlying lesion as well [Figure 3]b. No recurrence was noted while the patient performed activities of daily living without pain and discomfort.

Figure 1: The radiograph of the left forearm showing pathological fracture in radius diaphysis with abnormal bone morphology over a large area within the bone. There is thinning of cortices in multiple places

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Figure 2: The magnetic resonance images showing the fracture and expansion of bone with endosteal thinning of bone at multiple places along with edema over an extended segment within the bone (a and b). The axial images showing the multicameral lesion with fluid-filled cavities (c) and the characteristic fluid-fluid level noted along the lesion (d)

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Figure 3: The postoperative radiograph showing fixation with an intramedullary elastic nail (a), and the follow-up image showing good union without recurrence (b)

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patho

ABC is a metaphyseal, eccentric lesion with multilateral fluid-filled cavities that also shows fluid-fluid levels in classical radiological presentation.^[5] Its differentiation from UBC is required as ABC is more aggressive and bone destruction is more. ABC, though a benign lesion, is classified as a locally aggressive indeterminate tumor.^[6] Differentiation between ABC and telangiectatic osteosarcoma is important in dubious cases. The fluid usually is hemorrhagic, but clear fluid may also be found in ABC, whereas hemorrhagic fluid can also be found in UBC in case of trauma.^[2],[6] The differentiation becomes more crucial in some of the lesions mimicking aggressive neoplasm due to serious bone destruction. ABC can be secondary in 30% of cases in multiple preexisting lesions.^[7] Giant cell reparative granuloma and soft tissue ABC are considered other variants of ABC. The eccentricity and expansile nature described in metaphyseal ABC were not seen in our case with diaphyseal involvement. One reason may be hard diaphyseal cortical bone limiting its expansion. MRI has been examination of choice following radiographs to delineate multiple fluid-filled cavities and fluid levels that are highly suggestive if not specific to ABC. It may also contain sold tissue element also. Biopsy is essential to diagnosis and may be combined in selective cases in the form of curettage biopsy or “curopsy.” ABC has been associated with genetic rearrangement of USP6 gene (localized to 17p13), and one case of recurrent lesion containing multinucleate giant cells treated with denosumab is reported.^[8] The lesion in that particular case over the proximal radius, finally diagnosed periosteal ABC, showed marked improvement and thus indicated an alternate pathway of research in this direction. Use of denosumab for containment of lesion or its use in lesions with surgically difficult anatomical location, as done in giant cell tumor, may be further evaluated. As our case has a long segmental involvement, surgical fixation with intramedullary implant was chosen as being inexpensive treatment in resource-limited environment. In addition to characteristic radiological findings, fine needle aspiration cytology can also be beneficial in low-resource settings as these lesions mostly have nonspecific features and presence of blood-rich mesenchymal cells with no overt neoplastic activity.^[9] Open biopsy directly from the lesion, which yields representative specimen, may be performed at the time of operative fixation and also in cases with noncharacteristic radiological location or features. The treatments described for ABC are many such as open curettage, en bloc resection, sclerotherapy, and embolization, and one of the meted is chosen aiming for no recurrence and complication. Endoscopic curettage has been found in recent times as less invasive option to open methods with promising results.^[10] Many uncommon presentations are frequently reported for this lesion in the medical literature, suggesting the spectrum of clinical variability of this lesion. As new researches in the future would reveal better knowledge of etiology and genetic nature of ABC in the future, the lesion has to be managed in a standard manner in compliance with surgical oncological principles.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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