Week 4 - Soft Tissue Tumors

Question 0

What is the most common type of genetic abnormality in soft tissue tumors?

Answer 0

Specific chrom. abnormalities (usually TRANSLOCATIONS).
Some chrom. abonormalities produce FUSION genes that encode chimeric transcription factors, leading to transcriptional DEREGULATION.

Question 1

What factors influence the prognosis of a soft tissue tumor?

Answer 1

1. Histological classification - immunohistochemical stains
2. Histological grade
3. Stage of the tumor - also determines chance of surgical excision
4. Tumors arising in superficial locations have better prognosis than deep seated tumors

Question 2

What type of cell gives rise to soft tissue tumors?

Answer 2

Mutations in Mesenchymal stem cells

Question 3

What is the typical pattern of spread of sarcomas when they metastasize?

Answer 3

Sarcomas usually metastasize via hematogenous routes (to lung and bone).

Question 4

What modality is most helpful in assessment of soft tissue tumors of the extremities?

Answer 4

Imaging studies (MRI)

Question 5

What is the classification scheme for mesenchymal/soft tissue tumors?

Answer 5

They are classified by types of tissue they recapitulate or differentiate to (fibrous tissue, muscle, vessels, nerves) - and in each histogenic category they are divided into benign and malignant (sarcoma) forms

-Some soft tissue tumors have no normal tissue counterpart

Question 6

What is the difference between NF-1 and NF-2 mutations? What do they cause?

Answer 6

They cause peripheral nerve sheath tumor! (NF2 more closely associated with schwannomas & NF1 with Neurofibromas)

• NF1 is much more common
• Both act as growth suppressors (tumor suppressors)

Question 7

Where is the NF1 mutation?

Answer 7

Chromosome 17, coding for neurofibromin (tumor suppressor)

Question 8

Where is the NF2 mutation?

Answer 8

Chromosome 22 coding for merlin (regulated membrane receptor signalling)