Age / Sex : 31 / M

Chief complaint: growing mass lesion at left hip

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

(Quiz는 quiz일 뿐이오니 답안은 한개만 보내주시기 바라오며, 복수의 답안을 보내주시는 분은 정답이 포함되어 있더라도 부득이 semi-correct answer로 처리토록 하겠습니다.)

Courtesy: 이영한(Young Han Lee), 연세대세브란스병원(Severance Hospital, Younsei University)

Malignant transformation of osteochondroma to chondrosarcoma (at the left proximal femur) in hereditary multiple exostoses

Discussion

Findings:

 A mass with thick and large cartilagenous
component and internal extensive calcification at anterior aspect of left
proximal femur

Multiple
exostotic mass at both humerus, both distal ulna

Diagnosis: Malignant transformation of osteochondroma to chondrosarcoma (at the left proximal femur) in hereditary multiple exostoses

Differential Diagnosis:

 Osteochondroma, enchondroma protuberans

Discussion:

Hereditary Multiple Exostoses (HME)

Characterized
by the development of multiple osteochondromas

Prevalence;
1:50,000 to 1:100,000 in Western populations

Autosomal
dominant pattern

The skeletal
distribution of lesions; Variable distribution

- Angular deformity & shortening can be combined

Complication

- Cosmetic
and Osseous Deformity

-Fracture

-Vascular compromise

-Neurologic compromise → Neurologic Sequelae

-Malignant transformation

Malignant transformation of osteochondroma

Occurs 1% of
solitary osteochondroma/ Occurs 3~5% in HME
patients

Almost arising in the cartilage cap of
the osteochondroma

-Rarely arise in the base of
osteochondroma stalk

Chondrosarcoma arising in an
osteochondroma

- 8% of all chondrosarcomas

- Usually solitary and a low histologic
grade (67%–85% of cases),

Lesions that
grow or cause pain after skeletal maturity

-Should be suspected of malignant transformation

Radiographic
features suggest malignancy

-Growth of a previously unchanged osteochondroma

-Irregular and indistinct lesion surface

-Focal
regions of radiolucency within the lesion

-Erosion or destruction
of the adjacent bone

-Significant
soft tissue mass containing scattered or irregular calcification

-Hyaline
cartilage cap thickness (more than 1.5cm thick); extremely important

References:

1.    
Imaging of osteochondroma: variants and complications with
radiologic-pathologic correlation, RadioGraphics 2000; 20:1407–1434

2.     Chondrosarcoma
in a family with multiple hereditary exostoses J Bone Joint Surg Br. 2000
Mar;82(2):261-6.

3.    
Diagnostic
Imaging musculoskeletal; 2010 Amirsys 2:100-105