Age / Sex : 37 / M

Chief complaint: Gradually enlarging right thigh mass (from 2 months
ago/ spontaneously)

Courtesy: 김현주(Kim Hyun-joo), 순천향대학교 서울병원 (Soonchunhyang University Seoul Hospital)

Extraskeletal myxoid chondrosarcoma

Discussion

Findings:

 CT: Low attenuating lesion in vastus lateralis
muscle with homogenous enhancement.

    Combined low attenuating non-enhancing
portion in inferior aspect of it (about 3.7x5.5x9.0 cm)

MRI: There
is about 4.3x6.2x7.0 sized T1 slight high and T2 bright high SI mass lesion in
anterior aspect of vastus lateralis muscle. The lesion shows strong enhancement
after contrast injection. There is combined direct invasion into the
subcutaneous fat layer in anterior aspect of the mass. There is nonenhancing
portion in distal portion of the mass.

Differential Diagnosis:

 Soft tissue sarcoma, such as liposarcoma, MGF,
leiomyosarcoma.

Diagnosis:
Extraskeletal myxoid chondrosarcoma with focal rhabdoid feature

Discussion:

 Extraskeletal
chondrosarcoma

• Relatively rare neoplasm


• approximately 2% of all
  soft-tissue sarcomas


• histologic type

ú  
myxoid(m/c),
mesenchymal, well-differentiated chondrosarcoma

• Extraskeletal myxoid
  chondrosarcoma

ú  
mean age :
50 years (4 ~ 92 years)

ú  
male
predominance

ú  
majority of
lesions arise in the extremities

       thigh : the single m/c location

• Extraskeletal mesenchymal
  chondrosarcoma

ú  
young adults
between 15 and 35 years of age

ú  
female predilection

ú  
head and
neck (brain, orbit, and meninges), musculoskeletal lesions (m/c : lower
extremity (particularly the thigh))

• Clinical symptoms

ú  
nonspecific

ú  
m/c finding
being a slowly enlarging painless soft-tissue mass.

• Image findings

ú  
Radiographs

       - nonspecific soft-tissue mass

       - areas of chondroid matrix
mineralization (much more frequent in mesenchymal chondrosarcoma)

       - Underlying bone erosion or
invasion, periosteal reaction : unusual

ú  
CT & MR
images

       - high water content -> low
attenuation on CT

       - very high SI on T2WI

       - Only mild peripheral to septal
enhancement

       - lower water content caused by the
intermixture of small cells and more limited cartilaginous tissue

       - similar to muscle density on CT
scans

       - Typically intermediate SI on T2WI

       - areas of necrosis : high SI on
T2WI

       - diffuse but heterogeneous
enhancement

References:

 Imaging of primary chondrosarcoma: Radiologic-Pathologic
correlation. Radiographics 2003;23:1245-1278.