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Enchondroma with Secondary Aneurysmal Bone Cyst
This case report describes an unusual case of an enchondroma with secondary aneurysmal bone cyst formation in the proximal femur of a 13-year-old male. Imaging showed a septated lytic lesion in the intertrochanteric region. Histology revealed lobulated cartilaginous proliferation without atypia surrounded by bone and blood-filled cystic spaces, consistent with a secondary aneurysmal bone cyst arising from the enchondroma. This is a rare occurrence, as cystic changes are not usually seen in enchondromas. The patient will need monitoring due to the higher recurrence risk of aneurysmal bone cysts compared to typical enchondromas.
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Enchondroma with Secondary Aneurysmal Bone Cyst
- 1. Case Report: Enchondroma in Secondary Aneurysmal Bone Cyst Skeletal Radiol. 2011 Nov;41(11):1475-‐8. Epub 2012 May 26
- 2. Introduc:on • Enchondroma are common benign car:laginous tumors • Most common in metaphyseal regions • Most common sites: Metacarpals, Metatarsals, Phalanges, Proximal humerus, and Femur • X-‐Ray: well-‐defined ly:c lesions, punctate intralesional lesions (giant cell tumor of bone, fibrous dysplasia, chondrosarcoma, and osteonecrosis • Histology: lobulated tumor composed of hyaline car:lage that lacks significant cellularity and atypia, lamellar bones surround the lobules Cys:c change in enchondroma is unusual case
- 3. Clinical History Male, 13 years old Medical Evalua:on Antalgic gait Exacerbated on daily exercises training Right groin pain radiated down the front of thigh
- 4. AP and lateral views of the right hip demonstra:ng a ly:c lesion with peripheral sclerosis of the right proximal femur
- 5. Axial and coronal CT demonstrates septated, ly:c lesion in the intertrochanteric region with significant thinning of the posterior cortex
- 6. T1-‐weighted, T2-‐weighted, T1 fat-‐satura:on post-‐contrast MRI studies demonstrates a septated mass with low T1 signal, increased T2 signal, and rim enhancement within the intertrochanteric region of the right femur
- 7. WORKUP Non-‐aggresive, mildly expansile, radioluscent Mul:lobulated, Thinning of septated mass lesion with cortex intralesional without with low T1, Fibrous density and obvious increase signal Dysplasia peripheral fracture T2, rim enhancement sclerosis in intertrochanteri c region of right femur
- 8. Opera:on Benign car:laginous lesion with significant cys:c fibroosseus component
- 9. Lobular car:laginous prolifera:on without significant atypia encircled by a rim of bone. Blood-‐filled cys:c spaces lined by benign spindle cells, giant cells, woven bone, and hemosiderin. Focal area with eosinophilic “cementum-‐like” fibrin reminiscent.
- 10. Discussion Aneurysmal cys:c changes occur secondary to number of pathologic lesions à never been reported in Enchondroma
- 11. Fibrous Dysplasia Radiographic in this case: Fibrous Dysplasia X-‐Ray: Radiolucent lesion with ‘ground-‐glass’ opacifica:on Histology: prolifera:ng fibroblasts with osteoid trabeculae FD with massive chondroid differen:a:on à Fibrocar:laginous Dysplasia (FCD) Rare occasions: Calcifica:on may be so extensive à mimicking Enchondroma or Chondrosarcoma
- 12. Aneurysmal Bone Cyst Aneurysmal Bone Cyst (ABC) are benign osteoly:c lesions Blood-‐filled spaces separated by connec:ve :ssue septae Common sites: Long bones of lower extremity, and posterior of spine Primary and secondary ABC
- 13. Pathophysiology of Secondary ABC (Jaffe et al., 1942) Primary lesion ini6ates an intraosseus AVM Hemorrhagic “blow-‐out” in the preexis6ng lesion Secondary reac6ve lesion of bone The cyst may obliterate the original morphology and obscure the true nature of the preceding lesion
- 14. Aneurysmal Bone Cyst Recurrence rate of Enchondroma with treated intralesional cure`age is extremely low (<1%) Recurrence rate of ABC is more aggressive and have higher rate ( <40%), Recurencees within 2 years from surgery à monitored for at least 2 years
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- 21. BUBBLY LYTIC BONE LESIONS • F : Fibrous Dysplasia or Fibrous Cor:cal Defect • O: Osteoblastoma • G : Giant cell tumour (GCT) • M : Metastases • A : Aneurysmal Bone Cyst (ABC) • C : Chondroblastoma or Chondromyxoid fibroma • H :Hyperparathyroidism (Brown Tumor) • I : infec:on (Osteomyeli:s) • N : Non-‐ossifying Fibroma • E :Enchondroma or Eosinophilic Granuloma • S : Simple Bone Cyst AJR August 2009 vol 193 no. 2 W79-‐W94
- 22. Distribu:on of Lesions Enchondroma Fibrous Dysplasia ABC GCT Layout and distribuLon: Frank Gaillard 2009, Line drawing of skeleton: Patrick Lynch 2006, CreaLve Common NC-‐SA-‐BY
- 23. Enchondroma Benign medullary car:laginous neoplasm Childhood to early adulthood (10-‐30 y.o) Arise from chondrocytes composed of mature hyaline car:lage X-‐Ray and CT: 1-‐2 cm non-‐aggressive ly:c lesions, endosteal scalloping, chondroid calcifica:on, periosteal reac:on (-‐),sof :ssue mass (-‐) MRI: Intermediate-‐low signal T1WI, high signal T2WI Treatment and Prognosis: No treatment à cure`age and bone grafing
- 27. Fibrous Dysplasia • Benign tumour-‐like congenital process • Defect in osteoblas:c differen:a:on and matura:on, with progressive replacement of normal bone with immature woven bone • Children and yound adults, < 30 y.o • X-‐Ray and CT: Well circumscribed cys:c or sclero:c lesion, Ground-‐glass opacity, Endosteal scalloping, intact bone • MRI: Heterogenous Intermediate signal T1WI, heterogenous low signal T2WI • Treatment: no treatment à surgical decompression
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- 31. Aneurysmal Bone Cyst • Benign expansile tumor-‐like bone lesion, contain numerous blood filled channels • Children and adolescents (<20 y.o) • X-‐Ray : sharply defined, expansile osteoly:c lesions, with thin sclero:c margins • CT: fluid fluid levels • MRI: low signal of T1 and T2, • Treatment :Opera:ve (Bone curretage and Grafing)
- 37. Giant Cell Tumor Benign, metaepiphysis of long bones Early adulthood ( 20-‐ 50 y.o) Single lesions (knee, distal radius, sacrum) X-‐Ray and CT : occurs only with a closed epiphyseal plate, ar:cular surface, well defined with non-‐ sclero:c margin, periosteal reac:on (10-‐30% cases), no calcifica:on MRI: low signal in T1WI and T2WI Angiography: hypervascular tumor with the rest being hipo/avascular
- 39. ENCHONDROMA VS LOW GRADE CHONDROSARCOMA
- 41. Unicameral (Simple) Bone Cyst Fallen-‐Fragment sign