Fig. 4
Dedifferentiated liposarcoma. a This core needle biopsy of a large retroperitoneal mass from a 63-year-old man shows a variably cellular spindle cell neoplasm. b The tumor is composed of fascicles of mildly atypical, mitotically active spindle cells. The histologic appearances are not distinctive. c Immunohistochemistry for MDM2 shows strong nuclear staining. d Fluorescence in situ hybridization (FISH) performed on a cytologic smear from a corresponding fine needle aspiration shows multiple orange signals with a probe directed against chromosome 12q15 (MDM2) and two normal green signals with a probe directed against the chromosome 12 centromere, indicating high-level amplification of MDM2. This is a characteristic feature of dedifferentiated liposarcoma (and well-differentiated liposarcoma)
