= uncommon spindle cell tumor arising in dermis typically spreading into subcutaneous tissue + muscle

Frequency: 6% of all soft-tissue sarcomas

Age: mostly adolescence

Location: trunk (50%)

Site: classified as skin tumor (= cutaneous lesion)

CT:

• well-defined nodular subcutaneous lesion without calcification

MR:

• unmineralized small nodule / large mass
• nonspecific signal intensity:
  • hypointense on T1WI
  • hyperintense relative to fat on T2WI
  • ± heterogeneous foci of hemorrhage, myxoid change, necrosis
• linear extension along skin surface
• moderate enhancement