Flashcards in Week 4 - Soft Tissue Tumors Deck (9)
What factors influence the prognosis of a soft tissue tumor?
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
What is the most common type of genetic abnormality in soft tissue tumors?
Specific chrom. abnormalities (usually TRANSLOCATIONS).
Some chrom. abonormalities produce FUSION genes that encode chimeric transcription factors, leading to transcriptional DEREGULATION.
What type of cell gives rise to soft tissue tumors?
Mutations in Mesenchymal stem cells
What is the typical pattern of spread of sarcomas when they metastasize?
Sarcomas usually metastasize via hematogenous routes (to lung and bone).
What modality is most helpful in assessment of soft tissue tumors of the extremities?
Imaging studies (MRI)
What is the classification scheme for mesenchymal/soft tissue tumors?
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
What is the difference between NF-1 and NF-2 mutations? What do they cause?
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)
Where is the NF1 mutation?
Chromosome 17, coding for neurofibromin (tumor suppressor)