Soft tissue tumours and the periphery

Question 1

What are the histological findings in desmoids

Answer 1

Histologically, desmoids are characterized by a monoclonal fibroblastic proliferation appearing as small bundles of spindle cells in an abundant fibrous stroma.

The fibroblasts have a propensity to concentrate at the periphery of the lesion, and the cellularity is low.

The infiltrative connective tissue process may resemble that of a low-grade fibrosarcoma, but the cells lack nuclear and cytoplasmic features of malignancy.

There are usually few mitotic figures and necrosis is absent.

Histologically, sporadic and FAP-associated desmoids are indistinguishable.

Question 2

What is the appropriate resection margin for a desmoid tumour

Answer 2

negative margins

wide margins do not appear to confer an advantage

Question 3

When is close observation appropriate in desmoid tumours

Answer 3

Desmoids have an unpredictable clinical course, and close observation is an acceptable strategy for stable, asymptomatic primary or recurrent desmoids, particularly if resection would entail major morbidity

Question 4

When is surgery recommended in desmoids

Answer 4

When medically and technically feasible, desmoid tumors are treated by surgical resection with a negative margin

Question 5

What are the treatment options available in the management of desmoid tumours

Answer 5

Observation

Medical management

• TKI (Sorafenib)
• Several other therapies may be of assistance but as the spontaneous regression rate is high (~20%) whether they actually improve outcomes is unclear
  
  • tamoxifen
  • NSAIDS
• Cytotoxic chemotherapy is effective but rarely indicated
  
  • on the SMA etc

Surgery

Radiation

• NB: post radiation response is slow and may take years to shrink, but, radiation is effective

Question 6

Histological features for grading of sarcoma

Answer 6

Tumour necrosis

Mitotic rate

Degree of differentiation

Question 7

Sarcoma epidemiology

How might they be broadly subcategorised

Answer 7

Sarcomas account for 1% of all adult cancers

They may be broadly categorised into soft tissue and bone sarcomas

Question 8

What genetic syndromes and enviromental factor are associated with sarcoma development

Answer 8

NF1

p53

RB

Radiation

Question 9

What genetic condition is associated with development of desmoids

Answer 9

FAP (APC gene mutation)

Question 10

What genetic pathway is implicated in sporadic desmoid formation

Answer 10

CTNNB1

encodes beta catenin

Question 11

Desmoid aka

Answer 11

Aggressive fibromatosis

Question 12

What are the clinical features of carpel tunnell syndrome

• what is the anatomic basis for these features

Answer 12

The clinical features are of sensory and motor disturbance to the hand in the distribution of the median nerve

• the median nerve is a mixed motor and sensory nerve derived from the medial and lateral cords of the brachial plexus
  
  • it receives fibres from all of the roots (C5-T1)
• Sensory
  
  • pain
    
    • over the palmar aspect of the radial 3_¹/_² digits
  • sensory disturbance
    
    • over the palmar aspect of the radial 3^₁/^₂ digits
      
      • importantly sensation to the radial aspect of the proximal palm (esp over the thenar eminence) is preserved
        
        • this is because the palmar cutaneous branch crosses outside the flexor retinaculum
  • Motor
    
    • Thenar wasting and decreased thumb flexion and opposition
      
      • the thenar muscles are suplied by the recurrent branch of the median nerve
        
        • this is the first branch off the nerve after passing through the flexor retinaculum
          
          • opponens pollicis brevis and flexor policis brevis as well as abductor policis brevis and the first 2 lumbricals

Question 13

What are the structures that are at risk during carpel tunnel release

Answer 13

structures may be at risk if the incision is made either too ulnar, too radial or too distal

• ulnar
  
  • the ulnar artery and nerve
    
    • these run superficial to the flexor retinaculum in the canal of Guyon
• radial
  
  • the palmar cutaneous branch of the median nerve
    
    • branches off median nerve proximal to the flexor retinaculum and passes across superficial to the flexor retinaculum to supply sensation to the lateral aspect of the palm
  • the recurrent branch of the median nerve
    
    • usually branches distal to the flexor retinaculum but rarely may branch within the canal and perforate the flexor retinaculum.
• too distal
  
  • the superficial palmar arch
• other structures at risk include the long flexors of the thumb and the fingers and the median nerve itself