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ABDOMEN / Retroperitoneum   75 / M,  Abdominal mass
2018-05-01
About Author
Authors Shin Yong Moon
Institution Asan Medical Center
E-mail cjimage@amc.seoul.kr
About Case
Chief complaint
or Title
Abdominal mass
Subspecialty ABDOMEN / Retroperitoneum
Classification Neoplasm, Malignancy / sarcoma
Age 75 Sex M
Difficulty For resident, For specialist
Modality CT
Case Figures
Click above Figure for more images.
Questions
What is your diagnosis of retroperitoneal mass
Answer
Diagnosis 3 Liposarcoma
Comments

Answer 3. Liposarcoma



영상소견에서 뚜렷한
Fat이 안보이는 liposarcoma 증례





Case A: DEDIFFERENTIATED  LIPOSARCOMA  WITH 
MYOGENIC  DIFFERENTIATION,    20.0 x 14.0 x 12.0 cm,  RETROPERITONEUM,  ( See 
note )



      
with  1)  mitosis: 
up  to  18/10 HPF.



             2) 
necrosis:  not  identified.



            
3)  no  involvement 
of  kidney,  spleen, 
large  intestine  and



                 pancreas  parenchyma.



            
4)  clear  external, 
pancreatic,  large  intestinal 
proximal



                 and  distal 
resection  margins.



            
5)  no  metastasis 
in  2  regional 
lymph  nodes  ( 0/2 )



: - The 
results  of  immunohistochemical  staining:



    
CD117,  ( - );  CD34, 
( - );  SMA,  ( + ); 
desmin,  ( + );     MDM2, 
( + ); 



CDK4,  ( + );  S-100, 
( - );     Ki-67  labeling 
index,  ( about  40 % ).



 





 



Case B



 





Cut 
surface:  yellowish  white, 
myxoid  with  focal 
necrosis



MALIGNANT 
SPINDLE  CELL  NEOPLASM, 
CONSISTENT  WITH 



DEDIFFERENTIATED 
LIPOSARCOMA



 





Liposarcoma is the most common primary
retroperitoneal malignant soft tissue tumor and is divided into five subtypes,



  1. well differentiated,

  2. dedifferentiated,

  3. myxoid,

  4. pleomorphic,

  5. mixed types according to the
    2002 WHO histologic classification of soft tissue tumors

     













Dedifferentiated liposarcoma(DDL) is a
high-grade nonlipogenic sarcoma that arises in the background of a preexisting
well-differentiated liposarcoma. Dedifferentiated liposarcoma has a worse
prognosis than other subtypes because it has a higher risk of local recurrence
and distant metastasis.



DDL is a bimorphic neoplasm in which a
well-differentiated liposarcoma is juxtaposed with a high-grade nonlipogenic
sarcoma. On histopathology and CT images, the areas of well-differentiation
contain fatty component. On the other hand, the areas of dedifferentiation
display more various components. The most common dedifferentiated component is
undifferentiated pleomorphic sarcoma (previously called malignant fibrous
histiocytoma) or fibrosarcoma; however, rhabdomyosarcomatous,
leiomyosarcomatous, or osteosarcomatous component were also included in 10% of
the cases..



So on CT, Adipose tissue (below 30 HU),
soft tissue (34~76 HU) and the tissue with borderline density can be observed
in DDL mass.
Calcification or ossification has been reported
as a sign of dedifferentiation. An enhancing or centrally necrotic nodule may
be indicative of a dedifferentiated component in DDL.
On
MRI, the most of dedifferentiated component of DDL typically have nonspecific
findings, low to intermediate signal intensity on T1-weighted MR images and
intermediate to high signal intensity on T2-weighted MR images.



 



Conclusion



Dedifferentiated liposarcomas present
various spectra of imaging findings. It may appear as other types of
liposarcoma or other malignant retroperitoneal tumor.




References Hong SH, Kim KA, Woo OH, et al. Dedifferentiated liposarcoma of retroperitoneum: spectrum of imaging findings in 15 patients. Clin Imaging. 2010;34(3):203-210
Song T, Shen J, Liang BL, et al. Retroperitoneal liposarcoma: MR characteristics and pathological correlative analysis. Abdom Imaging. 2007;32(5):668-674.
Keywords Retroperitoneum, Liposarcoma,
Attachment File -

Number of Applicants : 32
Correct Answer 7
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