Chondroblastoma of the Patella With Aneurysmal Bone Cyst

n ase Report hondroblastoma of the Patella With neurysmal one yst Honglue Tan, M; Mengning Yan, M; ing Yue, M; Yiming Zeng, M; You Wang, M abstract Full article available online at Healio.com/Orthopedics. Search: 20131219-23 hondroblastoma of the patella is rare. neurysmal bone cysts, which develop from a prior lesion such as a chondroblastoma, are seldom seen in the patella. The authors report a case of a 36-year-old man who presented with 2 years of right knee pain without calor, erythema, pain on palpation, or abnormal range of motion. Radiological studies suggested aneurysmal bone cyst. The lesion was excised with curettage and the residual cavity filled with autogenous. Histopathology revealed chondroblastoma associated with a secondary aneurysmal bone cyst. In the follow-up period, the patient demonstrated normal joint activities with no pain. Normal configuration of the patella and bone union were shown on plain radiographs. The authors present a review of the literature of all cases of patellar chondroblastoma with aneurysmal bone cyst. This case is the 14th report of aneurysmal bone cyst arising in a chondroblastoma of the patella. ccording to the literature, computed tomography and magnetic resonance imaging are useful in the study of these lesions. The pathologic diagnosis is based on the presence of chondroblastoma and aneurysmal bone cyst. Treatment of this lesion includes patellectomy, curettage alone, and curettage with ing. espite the risk of recurrence of this lesion in the patella, the authors first recommend curettage followed by filling the cavity with. To protect the anterior tension of the patella intraoperatively, the bone window should be made at the medial edge of the patella to perform the curettage and ing. Figure: nteroposterior (left) and lateral (right) radiographs showing satisfactory autogenous bone graft of the patella 2 days postoperatively () and normal configuration of the patella and bone union 3 months postoperatively (). The authors are from the epartment of Orthopaedic Surgery (HT, MY, Y, YZ, YW), Shanghai Ninth People s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai; and Luoyang Orthopedics and Traumatology Institution (HT), Luoyang Orthopedic-Traumatological Hospital, Henan, hina. The authors have no relevant financial relationships to disclose. orrespondence should be addressed to: You Wang. M, epartment of Orthopaedic Surgery, Shanghai Ninth People s Hospital, Shanghai Jiao Tong University School of Medicine, No. 639, Zhizaoju Rd, Shanghai, hina, 213002 (hnlc.love@163.com). Received: pril 23, 2013; ccepted: September 5, 2013; Posted: January 15, 2014. doi: 10.3928/01477447-20131219-23 JNURY 2014 Volume 37 Number 1 e87

n ase Report T umors of the patella are rare. Only a few studies have reported these lesions, and most are case reports.1-17 The most frequent tumors in this location are giant cell tumor, chondroblastoma, and aneurysmal bone cyst.7,8 hondroblastoma accounts for 1% to 3% of all primary benign bone tumors and 22% of benign bone tumors in the patella.8,9 neurysmal bone cyst accounts for 1% of primary bone lesions and 4% to 7% of all benign patellar tumors.9,10 Secondary aneurysmal bone cysts are occasionally observed in giant cell tumor or chondroblastoma.7,11 In the current study, the authors report a case of chondroblastoma in the patella with aneurysmal bone cyst. ase Report 36-year-old man reported a 2-year history of right knee pain aggravated by exercise and improved at rest. On physical examination, there was no joint effusion, no pain on palpation, and no skin calor. There was no difference in appearance of the right patella compared with the left, and the knee had full range of active motion. Laboratory studies, including a hemogram, erythrocyte sedimentation rate, and routine biochemistry of the joint fluid, were all within normal ranges. Plain radiographs demonstrated a radiolucent lesion in the right patella with well-defined, lobulated margins. thin cortex, thin septations, and a sclerotic rim were also observed (Figures 1-1). omputed tomography scan revealed an osteolytic lesion with septations and sclerotic margins in the middle portion of the patella (Figures 1-1). Magnetic resonance imaging showed a lobulated lesion occupying greater than 75% of the patella. In addition, horizontal fluid-fluid levels in the patella with normal cartilage structure were seen, suspicious for aneurysmal bone cyst (Figures 1E-1H). Intraoperatively, no abnormality was found in the soft tissue. The anterior bone cortex and cartilage structures were integrated (Figures 2-2). To protect the anterior tension of the patella, a 1.5 1-cm e88 E F G H Figure 1: Preoperative anteroposterior () and lateral () radiographs showing a multiloculated lytic lesion with sclerotic margins. xial computed tomography scans showing an osteolytic lesion with a thin cortex and septations (, ). Sagittal (E, F), axial (G), and coronal (H) magnetic resonance images showing lobulated lesions with low intensity on T1-weighted images and high intensity on T2-weighted images with multiple fluid-fluid levels. E F Figure 2: Gross findings of the patella and surgical procedure. The anterior bone cortex () and cartilage structures () were integrated. Osteolytic lesions (), containing serosanguinous fluid and dark-colored soft tissue (), were found in the patella. The lesions were thoroughly curetted (E) and filled with autogenous (F). bone window was made at the medial edge of the patella, keeping the dorsal periosteum of the small bone segment intact. The patellar cystic lesions displayed a septal pattern. oth the larger and smaller cavities with a connection under the thin septum contained serosanguinous fluid and dark-colored soft tissue (Figures 2-2). The osteolytic lesions were thoroughly curetted and filled with autogenous bone graft taken from the iliac crest. The bone window was then closed using the small bone segment of the patella and fixed with absorbable suture (Figures 2E-2F). The soft tissue and fluid were sent for histopathologic analysis. Postoperatively, the patient was managed with dorsal cast immobilization for ORTHOPEIS Healio.com/Orthopedics

n ase Report Figure 3: nteroposterior (left) and lateral (right) radiographs showing satisfactory autogenous bone graft of the patella 2 days postoperatively () and normal configuration of the patella and bone union 3 months postoperatively (). Figure 4: Light micrograph showing large polygonal cells embedded in a chondroid matrix. In the more cellular areas, the chondroid matrix was less obvious and the tumor cells were intermingled with multinucleated giant cells (hematoxylin-eosin stain; original magnification 20) (). Magnification of the boxed region in Figure 4 (original magnification 40) (). Light micrograph showing cystic spaces filled with blood (hematoxylin-eosin stain; original magnification 10 (). Magnification of the boxed region in Figure 4 (original magnification 20) (). 2 weeks, followed by static quadriceps exercises. uring the short follow-up period, the patient demonstrated normal joint activities with no pain. Normal configuration of the patella and bone union were shown on plain radiographs (Figure 3). On histopathology, hypocellular chondroid matrix with dispersed chondroblastlike cells were observed; on high-power views, polyhedral chondroblasts with distinct cytoplasmic borders, pale pink cytoplasm, and hyperlobulated nuclei intermingled with an osteoclastic type of benign multinucleated giant cells surrounding a poorly formed chondroid matrix were seen (Figures 4-4). Light microscopy also showed several walled cystic spaces filled with blood; within the fibrous septum were immature bone formation and a few multinucleated giant cells, compatible with aneurysmal bone cyst (Figures 4-4). ased on histopathology, chondroblastoma with aneurysmal bone cyst was diagnosed. iscussion JNURY 2014 Volume 37 Number 1 hondroblastoma is a rare benign cartilaginous neoplasm that typically occurs in the epiphyses of the tubular long bones in the second or third decades of life.10 The distal femoral and proximal tibial epiphyses are most frequently involved, followed by the proximal humerus.5-8 hondroblastoma is seen in conjunction with aneurysmal bone cyst in 10% to 15% of patients.12 Schajowicz and Gallardo18 reported that 17% of their cases of chondroblastoma showed cystic changes similar histologically to aneurysmal bone cyst.18 iesecker et al19 studied 66 cases of aneurysmal bone cyst and found that 32% were associated with another benign bone lesion, including 5 chondroblastomas. However, aneurysmal bone cyst occurring in chondroblastoma of the patella has not been frequently reported. hondroblastoma or aneurysmal bone cyst rarely occurs in the patella. Only 14 cases of chondroblastoma of the patella with aneurysmal bone cyst have been reported to date (Table). Of these 14 cases, 10 patients had joint pain and swelling, except for 2 patellar fractures. The swelling was due to the proximity of the patellar lesions to the joint. The association of patellar fracture with chondroblastoma or aneurysmal bone cyst alone is rare. Pathologic fracture of the patella due to chondroblastoma with aneurysmal bone cyst was reported in 2 (14.3%) patients (Table). Therefore, when knee pain and signs of swelling are seen in a young man with a patellar lesion, a pathological fracture may be present, and the diagnosis of chondroblastoma with aneurysmal bone cyst should be considered. Eccentric, osteolytic destruction with lobulated margins, thinned cortices, and a well-defined sclerotic rim are common radiographic findings in chondroblastoma of the patella. The presence of patel- e89

n ase Report Study Table Literature Review of hondroblastoma of the Patella With neurysmal one yst No. of Patients Sex/ ge, y Symptoms Pathological Fracture uration, y Treatment verage Followup, y Recurrence Lewis & ullough 13 1 M/20 Swelling and pain No 2 Patellectomy 6 No M/25 Swelling and pain No N/ Patellectomy N/ No Gottschalk et al 14 3 M/30 Swelling and pain No 0.6 Patellectomy N/ No F/15 Swelling and pain No 0.3 Initial curettage plus, final patellectomy Wolfe et al 15 1 F/13 Swelling and pain Yes 0.8 urettage plus Ghekiere et al 16 1 F/11 Swelling and pain No 1 Initial curettage, final curettage plus esnoyers et al 11 1 F/37 Swelling and pain No 2 Initial curettage plus, final curettage plus Trebse et al 17 1 M/24 Pain No 5 urettage plus Singh et al 7 4 Mean 23 Swelling and pain Fracture in 1 patient N/ urettage plus Ozan & Toker 10 1 M/26 Swelling and pain No 3 urettage plus urrent study 1 M/36 Pain No 2 urettage plus bbreviation: N/, not available. 1 Yes 1.5 No 5 Yes 6 Yes 2.5 No N/ N/ 1.5 No 1 No lar expansion may suggest formation of a secondary aneurysmal bone cyst, and fluid levels are observed only when secondary aneurysmal bone cyst is found. 7,11 omputed tomography may be useful to better characterize the osteolytic lesions, with a thin cortex and septations inside the lesion. Magnetic resonance imaging is useful to demonstrate the typical cartilaginous pattern and fluid layers distinctive for this tumor. 7,8 The presence of a hypocellular chondroid matrix with dispersed chondroblast-like cells and cystic spaces filled with blood are typical pathological features for this lesion. The treatment of chondroblastoma of the patella with aneurysmal bone cyst includes patellectomy, curettage alone, and curettage with ing. ccording to a literature review (Table), 7,10,11,13-17 single-stage patellectomy was performed in 3 patients; 2-stage patellectomy was performed in 1 patient due to recurrence after curettage and ; 2-stage curettage and was performed in 2 patients after curettage alone or curettage and ; and single-stage curettage and ing was performed in 8 patients. The selection of treatment depends on the size of the cyst and whether recurrence has occurred. If small, curetting with s may be sufficent; if large or recurrent, curettage and ing or patellectomy may be advised. Recurrence after curettage, with or without, occurred in 3 patients. espite the risk of recurrence of this lesion in the patella, the authors recommend curettage followed by filling the cavity with ; patellectomy is not the first choice because loss of the patella disturbs the biomechanics of the knee joint, ultimately leading to early osteoarthritis. To protect the anterior tension of the patella intraoperatively, the bone win- e90 ORTHOPEIS Healio.com/Orthopedics

n ase Report dow should be made at the medial edge to perform curettage and ing. onclusion hondroblastoma with aneurysmal bone cyst should be suspected in a young patient with an osteolytic lesion of the patella. It is a localized lesion that demonstrates osteolytic destruction with lobulated margins, thinned cortices, fluid levels, and a well-defined sclerotic rim. omputed tomography and magnetic resonance imaging are useful in the study of these lesions. The pathologic diagnosis is based on the presence of chondroblastoma and aneurysmal bone cyst. urettage followed by filling the cavity with is recommend. References 1. Kransdorf MJ, Moser RP, Vinh TN, oki J, allaghan JJ. Primary tumors of the patella: a review of 42 cases. Skeletal Radiol. 1989; 18(5):365-371. 2. Ferguson P, Griffin M, ell RS. Primary patellar tumors. lin Orthop Relat Res. 1997; 336:199-204. 3. O Mara JW Jr, Keeling J, Montgomery E, aron. Primary lesions of the patella. Orthopedics. 2000; 23(4):328, 348, 370, 376-377. 4. Mercuri M, asadei R. Patellar tumors. lin Orthop Relat Res. 2001; 389:35-46. 5. hagat S, Sharma H, ansal M, Reid R. Presentation and outcome of primary tumors of the patella. J Knee Surg. 2008; 21(3):212-216. 6. Saglik Y, Yildiz Y, asarir K, Tezen E, Güner. Tumours and tumour-like lesions of the patella: a report of eight cases. cta Orthop elg. 2008; 74(3):391-396. 7. Singh J, James SL, Kroon HM, et al. Tumour and tumour-like lesions of the patella: a multicentre experience. Eur Radiol. 2009; 19(3):701-712. 8. asadei R, Kreshak J, Rinaldi R, et al. Imaging tumors of the patella. Eur J Radiol. 2013; 82(12):2140-2148. 9. Gudi N, Venkatesh Reddy VR, hidanand KJ. hondroblastoma patella presenting as a pathological fracture. Indian J Orthop. 2008; 42(1):100-101. 10. Ozan F, Toker G. Secondary aneurysmal bone cyst of the patella. cta Orthop Traumatol Turc. 2010; 44(3):246-249. 11. esnoyers V, harissoux JL, ribit F, rnaud JP. neurysmal bone cyst of the patella: a case report and literature review. Rev hir Orthop Reparatrice ppar Mot. 2000; 86(6):616-620. 12. Suneja R, Grimer RJ, elthur M, et al. hondroblastoma of bone: long-term results and functional outcome after intralesional curettage. J one Joint Surg r. 2005; 87(7):974-978. 13. Lewis MM, ullough PG. n unusual case of cystic chondroblastoma of the patella. lin Orthop Relat Res. 1976; 121:188-190. 14. Gottschalk F, Solomon L, Isaacson, Schmaman. neurysmal bone cysts of the patella secondary to chondroblastoma: case reports. S fr Med J. 1985; 67(3):105-106. 15. Wolfe MW, Halvorson TL, ennett JT, Martin P. hondroblastoma of the patella presenting as a knee pain in an adolescent. m J Orthop. 1995; 24(1):61-64. 16. Ghekiere J, Geusens E, Lateur L, Samson I, Sciot R, aert L. hondroblastoma of the patella with a secondary aneurysmal bone cyst. Eur Radiol. 1998; 8(6):992-995. 17. Trebse R, Rotter, Pisot V. hondroblastoma of the patella associated with an aneurysmal bone cyst. cta Orthop elg. 2001; 67(3):290-296. 18. Schajowicz F, Gallardo H. Epiphysial chondroblastoma of bone: a clinico-pathological study of sixty-nine cases. J one Joint Surg r. 1970; 52(2):205-226. 19. iesecker JL, Marcove R, Huvos G, Miké V. neurysmal bone cysts: a clinicopathologic study of 66 cases. ancer. 1970; 26(3):615-625. JNURY 2014 Volume 37 Number 1 e91