Case 37

A 50-year-old male with a 6.7 cm thigh mass and here is the biopsy.

1. What stains you would like to order?

   
   

IHC

• Keratin
• S100
• SOX10
• CD34

See All Options

You can vote for more than one answer.

2. The tumors are classically positive for S100 however, in this form it's negative, but the tumor is positive for SOX11. What's the molecular for this entity?

   A: FUS-CREB

   B: EWSR1-ERG

   C: BCOR rearrangement

   D: GLI rearrangement

   E: FUS-DDIT3

Answer

This is a case of round cell liposarcoma or high-grade myxoid liposarcoma. The molecular findings are DDIT3 with FUS or EWSR. In it's form, it no longer shows the classic morphology of myxoid liposarcoma (chicken wire curvilinear vessels, myxoid or edematous background, lipoblast). SOX11 can be a useful marker in this setting.

References: https://tumourclassification.iarc.who.int/chaptercontent/33/16

Xu S, Dong Y, Huo Z, Yu L, Xue J, Wang G, Duan Y. SOX11: a potentially useful marker in surgical pathology: a systematic analysis of SOX11 expression in epithelial and non-epithelial tumours. Histopathology. 2019 Feb;74(3):391-405. doi: 10.1111/his.13757. Epub 2018 Dec 2. PMID: 30221780.

Case credit: UCSD Pathology

Author: Wangpan Jackson Shi, MD