Oncology and Wound reconstruction

Question 1

What is the most important thing to do that guides our decision we make about a case?

Answer 1

Incisional biopsy!

Question 2

What is the difference between an incisional biopsy and an excisional biopsy?

Answer 2

Incisional: removing just a piece of tissue to submit for histopathology

Excisional: the entire mass is removed

Question 3

Which other preoperative diagnostic test can we do in combination with an incisional biopsy?

Answer 3

FNA - rule in/can’t rule out
FNA’s are most useful for mast cell tumours. Cannot grade neoplasia with an FNA.

Question 4

What are the indications for an incisional biopsy?

Answer 4

Any mass, large masses, location - planning, suspect malignant disease.

Preserves the lesion dimensions, they are not cost prohibitive (sedation & local)

Question 5

What are the indications for an excisional biopsy?

Answer 5

-> very small masses where incisional biopsy is difficult
-> Where FNA doesn’t give us information
-> Suspecting benign disease

Question 6

Why is it important that we ensure minimal manipulation of a tumour when surgically removing it?

Answer 6

-> Exfoliation - can exfoliate with manipulation leaving cancer cells behind
-> Release of cytokines - mast cell tumours - histamine (can give antihistamines)

-> Cover the surface of the mass/skin with ioban to ensure minimal manipulation

Question 7

Complete surgical excision - what is important about the margins?

Answer 7

All tissue planes must be cut at the same margin

Question 8

What is the deep (biological) margin?

Answer 8

These are structures such as fascia, tendons, cartilage - collagen rich and low blood supply provides a natural barrier to cancer

Question 9

Marginal excision, wide excision, radical excision - what are the differences?

Answer 9

Marginal: En bloc removal of tumour and pseudocapsule - “shell out” benign tumours like lipomas

Wide excision: En bloc removal of tumour and pseudocapsule - margin (lateral and deep) of normal tissue (1-3cm) - for well contained malignant disease such as cutaneous melanoma, plasmacytoma, mast cell tumour (grade 1,2), soft tissue sarcoma (grade 1-3)

Radical excision: removing the entire compartment - en bloc removal of tumour and entire tissue compartment - for infiltrative, malignant disease, amputation (digit, limb, tail, pinna, nasal planum) - locally aggressive disease such as osteosarcoma

Question 10

When submitting a tissue for histologic examination, how can we “mark” the surgical site/margin?

Answer 10

Identify cut margin lateral and deep with suture tags or dye

Question 10

What should be considered when planning and excision of a mass?

Answer 10

Consider the diagnosis! - malignant vs. benign

Curative intent - MUST get it all!
Don’t excise a lesion when you know you cannot completely excise the gross disease

Question 11

Where do mast cell tumours like to metastasize to and what are the distant sites?

Answer 11

Metastasis: Regional lymph nodes, liver, spleen - general enlargement (take FNA)
Distant sites: Organs, bone marrow

Question 12

What ist the treatment of choice for a mast cell tumour?
What is the adjunct therapy?

Answer 12

Surgical excision!
margin for excision depends on the grade
Grade 1: 1 cm lateral margin
Grade 2: 2 cm lateral margin
Grade 3: 3 cm lateral margin
Deep margin most difficult
Also remove draining lymph nodes

Adjunct therapy: Chemotherapy, Radiation

Question 13

What is the treatment of choice for a soft tissue sarcoma?

Answer 13

Excision is often difficult (depending on location), deep margin is important
May need radical excision (amputation)

They are slow to metastasize but can! (consider with grade 3)

Question 14

What is the treatment of choice for a lipoma?

Answer 14

Surgical excision - based on form (marginal resection or radical)

Question 15

What are dirty margins?

Answer 15

Dirty margins describe tumour cells that extend to the edge of the removed tissue, indicating that tumour cells still remain in the animals body

-> Revisit surgical options - en bloc excision or radical excision of previous site
-> Adjunctive therapy: Radiation, chemotherapy

Question 16

What are the 3 stages of wound healing, their characteristics and what are the approximate times?

Answer 16

Inflammation and debridement: 0-5 days
-> inflammatory cells eliminate contaminants and non-viable tissue (important to maintain moist wound environment)

Repair: 5-21 days
->Granulation tissue forms, epithelialisation occurs (maintain moist wound environment)

Maturation: 21 days +
-> Collagen reorganises

Question 17

Skin tension lines - which way should an incision be made?

Answer 17

Making an incision parallel to skin tension line so that we have more skin to work with. If it is made perpendicular it is more likely to pull apart.

Question 18

When we are planning to close a defect in a straight line, then which shape should the excision be made?

Answer 18

Make an ellipse excision

Question 19

Tension relieving techniques - what is meant by undermining and closure?

Answer 19

It is crucial that before we are placing the skin sutures that the edges sit together in a relaxed way - undermining the tissue means loosening the connective tissue underneath the panniculus muscle so we maintain blood supply that is so important and unique in dogs and cats. (insert close scissors under the skin and open) this way the skin can move to the middle where the incision is.

Question 20

What is another technique to do tension relieving sutures?

Answer 20

Walking sutures - place sutures into wound bed and suture into skin (offsetting the two) this “walks” the skin towards the midline.

Question 21

What is important to consider when planning the use of local skin flaps in surgery?

Answer 21

Have to assess neighbouring skin tension
Have to assess the affect of second intention healing (contraction, friable epithelial surface, bandaging, time)

Question 22

What do we call a skin flap where we leave a part of the skin attached?

Answer 22

Single pedicle advancement flap

-> local flap
-> has random cutaneous blood supply (we don’t know which blood vessels are supplying the flap)
-> utilises loose skin at wound edge

Question 23

When using a single pedicle advancement flap, do we have to make the incision parallel or perpendicular to wound axis/line of tension?

Answer 23

Perpendicular!

Question 24

When we are using 2 flaps for a single pedicle advancement flap what do we call that?

Answer 24

H plasty (pedicle flap from both directions)

Question 25

Which advancement flap is used only for surgery in the mouth?

Answer 25

Bipedicle advancement flap

-> creates a secondary defect - close or heal by 2nd intention
-> utilises loose skin away from wound edge
-> incisions parallel to wound axis/line of tension

Question 26

What is a transposition flap and how does it work?

Answer 26

Creating a single pedicle next to the original incision point usually from lose skin being used to cover the defect - using this technique creates a secondary defect.

Question 27

Where else on the body of dog/cat would be enough skin to use/create a flap? What do we call these?

Answer 27

Axilla and Inguinal “flank” flaps
Utilises the skin in axilla and inguinal folds (random cutaneous blood)

Triangulation of skin (remains attached at one length of fold) and rotation into defect. Cut edges are being closed primarily. Useful for proximal limb and trunk defects.

Question 28

Which skin flaps are good to use for cats but not really for dogs?

Answer 28

Distant skin flaps
-> Single (hinge) and bipedicle pouch flaps
(leg is attached to trunk and left for at least two weeks for vessels to re-vascularise)

Question 29

What are the indications for the use of axial pattern flaps?

Answer 29

When a defect cannot be closed primarily with local technique and where second intention healing is undesirable

Question 30

What are the advantages of axial pattern flaps?

Answer 30

Advantages: reliable blood supply (blood supply not random - known point of origin of cutaneous artery), full-thickness, haired, vascular coverage

Question 31

What are the indications for the use of free skin grafts?

Answer 31

Defect cannot be closed primarily with other techniques, requires an area where we can limit movement (mostly used for distal limb), where second intention healing is undesirable

Question 32

What does the wound need in preparation before using free skin grafts?

Answer 32

Need a healthy bed of granulation tissue, smooth surface and free from infection!