Cystic and degenerative changes (more frequent than in counterpart in deep somatic soft tissue)
IHC
ER and PR
Positive
M, male; F, female; HPF, high power fields; IHC, immunohistochemistry; ER, estrogen receptor protein; PR, progesterone receptor protein. The authors concluded that a smooth muscle tumor of retroperitoneum with >10 mitoses/50 HPF should be regarded as “smooth muscle tumors of uncertain malignant potential.”