Flashcards in Basic Sciences Deck (118)
Where are sarcomas most likely to be found?
In the extremities
What are sarcomas?
Malignant tumours fo mesenchymal origin.
What are the origins of sarcomas? (3)
2. Soft tissue
3. Malignant fibrous histocytoma - sarcoma that may arise in both soft tissues and bone
Types of bone sarcoma? (3)
2. Ewings sarcoma (although non bony sites also recognised)
3. Chondrosarcoma - originates from chondrycytes.
Types of soft tissue sarcoma? (4)
1. Liposarcoma (adipocytes)
2. Rhabdomyosaroma (striated muscle)
3. Leiomyosarcoma (smooth muscle)
4. Synovial sarcomas (close to joints - cell fo origin not known, but NOT synovium)
General clinical features of sarcomas? (4)
1. Large (>5cm) soft tissue mass.
2. Deep tissue location or intra muscular location.
3. Rapid growth.
4. Painful lump.
Assessment of sarcomas?
Imaging of suspicious masses should utilise a combination fo MRI, CT and ultrasound.
Blind biopsy should not be performed prior to imaging and where required should be done in such a way that the biopsy tract can be subsequently included in any resection.
Epidemiology of Ewings sarcoma? (3)
1. Commoner in males.
2. Incidence of 0.3/1,000,000
3. Onset typically between 10-20 years.
Commonest site of Ewings sarcoma?
Location by femoral diaphysis is commonest site.
Histology of Ewings sarcoma?
Small round tumour.
Management of Ewings sarcoma?
Blood borne metastasis is common and chemotherapy is often combined with surgery.
Pathophysiology of osteosarcoma?
Mesenchymal cells with osteoblastic differentiation.
Epidemiology of osteosarcoma? (4)
1. 20% of all primary bone tumours.
2. Incidence of 5/1,000,000
3. Peak age 15-30.
4. Commoner in males.
Management of osteosarcoma?
Limb preserving surgery may be possible and many patients will receive chemotherapy.
Origins of liposarcoma?
Epidemiology of liposarcoma? (3)
1. Rare - 2.5/1,000,000.
2. They are the most common soft tissue sarcoma.
3. Affect older age group - usually >40 years of age.
Pathophysiology of liposarcoma? (3)
1. Located in deep locations such as retroperitoneum.
2. May be well differentiated and thus slow growing although may undergo de-differentiation and disease progression.
3. Many tumours will have a pseudocapsule that can misleadingly allow surgeons to feel that they can 'shell out' these lesions. In reality, tumour may invade at the edge of the pseudocapsule and result in local recurrence if this strategy is adopted.
Management of liposarcoma?
Usually resistant to radiotherapy, although this is often used in a palliative setting.
Pathology of malignant fibrous histiocytoma?
Tumour with large number of histiocytes.
Also described as undifferentated pleomorphic sarcoma NOS (i.e. cell of origin is not known).
Subtypes of malignant fibrous histocytoma? (4)
1. Storiform- pleomorphic (70%)
2. Myxoid (less aggressive)
3. Giant cell
Management of malignant fibrous histiocytoma?
Treatment is usually with surgical resection and adjuvant radiotherapy as this reduces the likelihood of local recurrence.
A 10 year old boy is admitted to the emergency department following a fall. On examination, there is deformity and swelling of the forearm. The ability to flex the fingers of the affected limb is impaired. However, there is no sensory impairment. Imaging confirms a displaced forearm fracture. Which of the nerves listed below is likely to have been affected?
Anterior interosseous nerve.
Forearm fractures may be complicated by neurovascular compromise. The anterior interosseous nerve may be affected. It has no sensory supply, so the defect is motor alone.
Features of the anterior interosseous nerve?
1. A branch of the median nerve that supplies the deep muscles of the front of the forearm - except the ulnar half of the flexor digitorum profundus.
2. It accompanies the anterior interosseous artery along the anterior of the interosseous membrane of the forearm - in the interval between the flexor pollicis longus and flexor digitorum profundus, supplying the whole of the former and (most commonly) the radial half of the latter, and ending below in the pronator quadratus and wrist joint.
Innervation of the anterior interosseous nerve? (3)
It classically innervates 2.5 muscles:
1. Flexor pollicis longus
2. Pronator quadratus
3. Radial half of the flexor digitorum profundus (the lateral two out of the four tendons).
These muscles are in the deep level of the anterior compartment of the forearm.
Which nerve supplies the majority of the skin on the palmar aspect of the thumb?
Median nerve supplies the cutaneous sensation to this region.
Features of the median nerve?
Path of median nerve?
It is formed by the union of a lateral and medial root respectively from the lateral (C5,6,7) and medial (C8, T1) cords of the brachial plexus.
The medial root passes anterior to the third part of the axillary artery.
The nerve descends lateral to the brachial artery, crosses to its medial side (usually passing anterior to the artery).
It passes deep to the bicepital aponeurosis and the median cubital vein at the elbow.
It passes between the two heads of the pronator teres muscle and runs on the deep surface of the flexor digitorum superficialis (within its fascial sheath)
Near the wrist it becomes superficial between the tendons of flexor digitorum superficialis and flexor carpi radialis, deep to the palmaris longus tendon.
It passes deep to the flexor retinaculum to enter the palm, but lies anterior to the long flexor tendons within the carpal tunnel.
Upper arm branches of median nerve?
No branches, although the nerve commonly communicates with the musculocutaneous nerve.
Innervation of median nerve in forearm? (7)
1. Pronator teres.
2. Pronator quadratus.
3. Flexor carpi radialis.
4. Palmaris longus.
5. Flexor digitorum superficialis.
6. Flexor pollicis longus.
7. Flexor digitorum profundus (only the radial half)
Branch of median nerve in distal forearm?
Palmar cutaneous branch