Soft Tissue

Question 1

Angiomyofibroblastoma of the vulva mist commonly expresses which immunohistochemical marker?

Answer 1

Benign myofibtoblastic rx
Bland stromal cells 
Desmin +
Occasionally CD34 and actins 
Always S100 negative (-)

Question 2

Which gene is most frequently mutated in classic blue Nevus ?

Answer 2

GNAQ or GNA11

Question 3

Important gene 🧬 mutations to know

1) FLCN
2) PTCH1
3) TSC1
4) PTEN
5) FH

Answer 3

1) FLCN - folliculin - Birt Hogg Dube $ , trichodiscoma and fibrofolliculoma
2) PTCH1 - Gorlin $, multiple BCCs, odontogenic keratocyst, Palmer/plantar pits
3) TSC1 - Tuberous sclerosis- facial angiofibromas and PEComas
4) PTEN - Cowden $. Trichilemmoma
5) FH - fumerate hydratase - HLRCC $

Question 4

NKX2.2 positive tumor

Answer 4

Ewing sarcoma (~85% of cases)

If CD99 is not strong - think of Ewing like sarcomas