CASE REPORT Open Access

Solid variant of aneurysmal bone cyst in the tibiatreated with simple curettage without bone graft:a case reportRumi Takechi1, Takashi Yanagawa1*, Tetsuya Shinozaki1, Toshio Fukuda2 and Kenji Takagishi1

Abstract

The solid variant of aneurysmal bone cyst (solid ABC) is rarely encountered in long bones and appropriatetreatment for this disease remains unclear. We experienced a 13-year-old boy suffering from pain in his left kneecaused by solid ABC. Simple curettage of the bone lesion without any adjuvant therapy and a bone graft gaveimmediate pain relief. Histological examination of the surgical specimen showed typical features of solid ABC, andcycloxygenase-2 (COX-2) expression was confirmed in giant cells with a background of spindle cells byimmunohistochemistry. Magnetic resonance imaging showed that soft tissue edema surrounding the lesion wasimproved two months after surgery and there was no indication of recurrence two years after surgery.If COX-2 secreted from the tumor induces soft tissue edema, simple curettage of the bone lesion seems to be areasonable treatment for solid ABC and is able to minimize invasive treatment of the patients.

Keywords: aneurismal bone cysts, curettage, cyclooxygenase 2

BackgroundThe term ‘solid variant of aneurysmal bone cyst (solidABC)’ was first described by Sanerkin et al. as a non-cys-tic bone lesion with histological features found in thesolid parts of a conventional aneurysmal bone cyst [1].Meanwhile, Jaffe et al. first reported giant cell reparativegranuloma (GCRG) as a reactive lesion to an intraosseoushemorrhage in the jaw [2], and Lorenzo et al. describedGCRG in the short tubular bones of the hands and feet[3]. The histological features of solid ABC resembledthose of GCRG, which indicated a close relationshipbetween the two conditions [1].Solid ABC commonly affects the axial skeleton and

short tubular bones of the hands and feet, and is rarelyencountered in the long bones. Ilaslan et al. reported 30cases of solid ABC in the long bones, eight of whichunderwent magnetic resonance (MR) imaging. MR imagefindings showed solid bone lesions in all eight cases andsurrounding edema in 50% [4]. With regard to the treat-ment, solid ABCs of short tubular bones have been

treated with resection, amputation, and curettage supple-mented with adjuvant therapies [5-7]; however, itremains unknown which treatment is most appropriatefor tumors in long bones. In addition, it is obscure whysolid ABC accompanies edematous lesions and how totreat the edema.Here, we report a case of solid ABC in the left tibia

treated by only curettage with radiological evaluation,and examined the cause of edema in solid ABC.

Case PresentationA 13-year-old boy was referred to our hospital on July2007 complaining of slight pain and swelling in his leftpopliteus. He initially noticed knee pain during kneemotion without any major trauma in February 2007 andswelling of his left popliteal fossa two months later. Onphysical examination, there was swelling without tender-ness and local heat of his left posterior knee. Laboratorydata were uniformly unremarkable, except for a highlevel of alkaline phosphatase. Plain radiographs showedan expansive and well-defined osteolytic lesion sur-rounded by a shell in the cortex of the metaphysis of theleft proximal tibia. Computed tomography (CT) of thetibia showed an osteolytic expansive lesion with cortical

* Correspondence: tyanagaw@med.gunma-u.ac.jp1Department of Orthopaedic Surgery, Gunma University Graduate School ofMedicine. 3-39-22, Showa, Maebashi, Gunma, 371-8511, JapanFull list of author information is available at the end of the article

Takechi et al. World Journal of Surgical Oncology 2012, 10:45http://www.wjso.com/content/10/1/45 WORLD JOURNAL OF

SURGICAL ONCOLOGY

© 2012 Takechi et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative CommonsAttribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction inany medium, provided the original work is properly cited.

thinning (Figure 1a). On MR imaging, the bony lesionwas iso-intense on T1 with a mixture of low and high sig-nal intensity on T2-weighted images with an edema-likesoft tissue lesion adjacent to the bony lesion (Figure 1b).First, needle biopsy of the soft tissue mass was performedbecause the lesion was suspected to be malignant. Histol-ogy revealed that the lesion was fibromuscular with lym-phoid tissue without malignancy, and surgical treatmentwas performed. Intraoperative biopsy of the white softtissue infiltrating the soleus muscle revealed that the softtissue lesion was similar to the needle biopsy specimenspre-operation. After the soft tissue was confirmed to bereactive to inflammation and without malignancy, thebone lesion, which was occupied with solid white tissue,was curetted without adjuvant therapy, such as phenoltreatment or bone grafting. Histological examination ofthe surgical specimens showed a solid variant of aneurys-mal bone cyst with belt-shaped giant cells against a back-ground of spindle cells and scattered osteoclasts (Figure2a). Immunohistochemistry revealed cyclooxygenase-2(COX-2) expressed in not only giant cells but also spindlecells (Figure 2b), which was confirmed by anti-humanCOX-2 antibody (IBL, Japan). The posterior knee painimmediately disappeared after surgery. On MR imagingat follow-up 2 months after surgery (Figure 3), the softtissue edema had markedly improved. There was norecurrence of the lesion two years after the operation(Figure 4) and the operated bone exhibited good remo-deling (Figure 5a, b)

DiscussionSolid ABC commonly originates from short bones andrarely affects long bones. The recurrence rate of lesionstreated with simple curettage is relatively high, andtherefore, amputation or curettage with adjuvant ther-apy, such as phenol and ethanol, has been applied tosolid ABC in the short bones by some authors [5-7].Oda et al. reported, however, that no patients had localrecurrence after curettage or intralesional resection [8].In the current case, simple curettage of the bony

lesion without adjuvant therapy and a bone graft couldcure solid ABC in a long bone. After the operation, thesurrounding soft tissue edema was markedly relievedand the bony lesion completely remodeled, which wasconfirmed with post-operative CT and MR images. Thecause of soft tissues edema surrounding the bone lesionof solid ABC remains unclear, although edema is one ofthe features of solid ABC on MR imaging. Some benigntumors with inflammation, such as osteoid osteoma andchondroblastoma, are known to produce prostaglandin,COX-2 and other cytokines related to inflammation[9-11]. In our solid ABC case, COX-2 was expressed ingiant cells and spindle cells. If cytokines from the bonelesion of solid ABC induce soft tissue edema, simplecurettage of the bony lesion seems to be a better surgerythan wide resection, including edematous soft tissues.There is a possibility that the edema was provoked notonly by COX-2 from the tumor but also by a small frac-ture of the shell-like cortex; however, if the cause of his

Figure 1 A 13-year-old boy with a solid ABC in the left tibia. a. CT showed an osteolytic expansive lesion with cortical thinning. b. The bonylesion showed a mixture of low and high signal intensity on T2-weighted MR images with an edematous lesion adjacent to the bony lesion.

Takechi et al. World Journal of Surgical Oncology 2012, 10:45http://www.wjso.com/content/10/1/45

Page 2 of 5

pain and edema was a fracture at the lesion, the symp-toms would have been relieved within 2 months. There-fore, we diagnosed that his pain and edema were mainlyinduced by the tumor.Recently, we and Hirn et al. reported that simple cur-

ettage without bone grafts for benign bone tumors, suchas giant cell tumor, chondroblastoma, enchondroma,simple bone cyst, and so on, in long bones gives suffi-cient bone strength to host bones [12,13]. Our previousstudy showed that no patients needed orthosis 3 monthsafter curettage for lesions of wide-ranging size (2-196cm3). This indicates that larger solid ABCs than in thecurrent report are expected to be cured with simple cur-ettage. Some authors reported that extensive curettageof the tumor may be more important than the use ofadjuvant therapies to prevent local recurrence, which

enabled us to use no adjuvant treatment after curettage[14,15].The typical MR imaging appearance of solid ABC is as

follows: a bony lesion is heterogeneous with a predomi-nantly high signal on T2-weighted images and edemaadjacent to the lesion was seen in 50% of cases [4].These findings may lead physicians to misdiagnose thisdisease as malignant. Radiologists and orthopedic sur-geons should keep in mind solid ABC with lytic bonelesions that have soft tissue edema to avoid unnecessaryovertreatment.

ConclusionWe experienced a solid ABC with surrounding soft tissueedema which was presumably induced by COX-2 fromthe tumor. Simple curettage of a bone lesion secreting

Figure 2 Photomicrographs showing a) belt-shaped giant cells against a background of spindle cells and scattered osteoclasts. Thesefeatures are compatible with solid ABC (hematoxylin-eosin x400). b) Immunohistochemical staining revealed COX-2 expressed in giant cells andspindle cells (x400).

Figure 3 MR imaging 2 months after surgery. Soft tissue edemareduced markedly.

Figure 4 MR imaging at most recent visit. There was no tumorrecurrence.

Takechi et al. World Journal of Surgical Oncology 2012, 10:45http://www.wjso.com/content/10/1/45

Page 3 of 5

COX-2 achieved an excellent result with immediatereduction of the edema and good remodeling of the cur-etted lesion. To minimize surgical invasion, diagnosis ofa lytic bone lesion with a sclerotic rim and surroundingsoft tissue edema is important.

ConsentWritten informed consent was obtained from the patient’sparents for publication of this Case report and any accom-panying images. A copy of the written consent is availablefor review by the Editor-in-Chief of this journal.

List of abbreviationsABC: aneurysmal bone cyst; COX-2: cycloxygenase-2; GCRG: giant cellreparative granuloma; MR: magnetic resonance; CT: computed tomography.

AcknowledgementsWe thank Ms Hiroe Miyahata from Gunma University Graduate School ofMedicine for her technical assistance in IHC analyses.

Author details1Department of Orthopaedic Surgery, Gunma University Graduate School ofMedicine. 3-39-22, Showa, Maebashi, Gunma, 371-8511, Japan. 2Departmentof Laboratory Sciences & Pathology, Gunma University School of HealthSciences, 3-39-22, Showa, Maebashi, Gunma, 371-8511, Japan.

Authors’ contributionsRT collected data, carried out the immunohistochemistry and draftedmanuscript. TY conceived of the design and helped to draft the manuscript.TF contributed to histological diagnosis. TS and KT revised manuscriptcritically for important intellectual content. All authors read and approvedthe final manuscript.

Competing interestsThe authors declare that they have no competing interests.

Received: 20 December 2011 Accepted: 20 February 2012Published: 20 February 2012

References1. Sanerkin NG, Mott MG, Roylance J: An unusual intraosseous lesion with

fibroblastic, osteoclastic, osteoblastic, aneurysmal and fibromyxoidelements. “Solid” variant of aneurysmal bone cyst. Cancer 1983,51:2278-2286.

2. Jaffe HL: Giant-cell reparative granuloma, traumatic bone cyst, andfibrous (fibro-oseous) dysplasia of the jawbones. Oral Surg Oral Med OralPathol 1953, 6:159-175.

3. Lorenzo JC, Dorfman HD: Giant-cell reparative granuloma of short tubularbones of the hands and feet. Am J Surg Pathol 1980, 4:551-563.

4. Ilaslan H, Sundaram M, Unni KK: Solid variant of aneurysmal bone cysts inlong tubular bones: giant cell reparative granuloma. AJR Am J Roentgenol2003, 180:1681-1687.

5. Wenner SM, Johnson K: Giant cell reparative granuloma of the hand. JHand Surg Am 1987, 12:1097-1101.

6. Dahlin DC: Giant-cell-bearing lesions of bone of the hands. Hand Clin1987, 3:291-297.

7. Yoshida T, Sakamoto A, Tanaka K, Matsuda S, Oda Y, Iwamoto Y: Alternativesurgical treatment for giant-cell reparative granuloma in the metacarpal,using phenol and ethanol adjuvant therapy. J Hand Surg Am 2007,32:887-892.

8. Oda Y, Tsuneyoshi M, Shinohara N: “Solid” variant of aneurysmal bonecyst (extragnathic giant cell reparative granuloma) in the axial skeletonand long bones. A study of its morphologic spectrum and distinctionfrom allied giant cell lesions. Cancer 1992, 70:2642-2649.

9. Greco F, Tamburrelli F, Ciabattoni G: Prostaglandins in osteoid osteoma.Int Orthop 1991, 15:35-37.

10. Kawaguchi Y, Sato C, Hasegawa T, Oka S, Kuwahara H, Norimatsu H:Intraarticular osteoid osteoma associated with synovitis: a possible roleof cyclooxygenase-2 expression by osteoblasts in the nidus. Mod Pathol2000, 13:1086-1091.

11. Uchikawa C, Shinozaki T, Nakajima T, Takagishi K: Cytokine synthesis bychondroblastoma: relation to local inflammation. J Orthop Surg (HongKong) 2009, 17:56-61.

12. Yanagawa T, Watanabe H, Shinozaki T, Takagishi K: Curettage of benignbone tumors without grafts gives sufficient bone strength. Acta Orthop2009, 80:9-13.

13. Hirn M, de Silva U, Sidharthan S, Grimer RJ, Abudu A, Tillman RM, Carter SR:Bone defects following curettage do not necessarily needaugmentation. Acta Orthop 2009, 80:4-8.

14. Blackley HR, Wunder JS, Davis AM, White LM, Kandel R, Bell RS: Treatmentof giant-cell tumors of long bones with curettage and bone-grafting. JBone Joint Surg Am 1999, 81:811-820.

Figure 5 X-ray findings of the lesion. Shell-like lesion on the posterior surface of the tibia before operation (a) completely disappeared andthe host bone had consolidated well 2 years after operation (b).

Takechi et al. World Journal of Surgical Oncology 2012, 10:45http://www.wjso.com/content/10/1/45

Page 4 of 5

15. Eckardt JJ, Grogan TJ: Giant cell tumor of bone. Clin Orthop Relat Res 1986,204:45-58.

doi:10.1186/1477-7819-10-45Cite this article as: Takechi et al.: Solid variant of aneurysmal bone cystin the tibia treated with simple curettage without bone graft: a casereport. World Journal of Surgical Oncology 2012 10:45.

Submit your next manuscript to BioMed Centraland take full advantage of:

• Convenient online submission

• Thorough peer review

• No space constraints or color figure charges

• Immediate publication on acceptance

• Inclusion in PubMed, CAS, Scopus and Google Scholar

• Research which is freely available for redistribution

Submit your manuscript at www.biomedcentral.com/submit

Takechi et al. World Journal of Surgical Oncology 2012, 10:45http://www.wjso.com/content/10/1/45

Page 5 of 5