Principles of Oncological Surgery

Question 1

Define…
1. En bloc.
2. Excisional biopsy.
3. Grade.
4. Histamine.
5. Lymphadenectomy.
6. Macroscopic tumour.
7. Marginal excision.
8. Tumour margin.

Answer 1

1. Remove all at the same time.
2. Surgery to remove the visible tumour without prior knowledge of cell type / grade.
3. Measure of malignancy.
4. Vasoactive substance stored in mast cells.
5. En bloc removal of a lymph node.
6. Visible to the naked eye.
7. Removal of a tumour using narrow margins.
8. Area of tissue that is removed around tumour. Often described as later and/or deep.

Question 2

Define…
1. Microscopic tumour.
2. Morbidity (surgical).
3. Palliation.
4. Prognosis.
5. Sentinel / draining LN.
6. Tumour thrombus.
7. Undifferentiated tumour.
8. Wide excision.

Answer 2

1. Invisible to the naked eye.
2. Temporary or permanent disability caused by surgery.
3. Easing severity of underlying condition without removing the cause.
4. Likely course of a condition such as a tumour.
5. LN draining a specific part of the body.
6. Tumour growing into a blood vessel (adrenal / spleen).
7. A tumour where the cells are not classifiable = measure of malignancy.
8. Removal of a tumour using wide margins decided by evidence for that tumour type at that site.

Question 3

1. Examples of benign epithelial tumours.
2. Examples of malignant epithelial tumours.

Answer 3

1. Adenoma, basal cell tumour, benign epithelial cysts / polyps, epithelioma, hamartomas, papilloma (warts), pilomatricoma, trichoblastoma / trichoepithelioma.
2. Adenocarcinoma, basal cell carcinoma, carcinoma, squamous cell carcinoma.

Question 4

1. Examples of common benign mesenchymal tumours.
2. Examples of less common benign mesenchymal tumours.
3. Examples of common malignant mesenchymal tumours.
4. Examples of less common malignant mesenchymal tumours.

Answer 4

1. Haemangiopericytoma, lipoma.
2. Benign nerve sheath tumours, fibroma, haemangioma, leiomyoma, osteoma.
3. Fibrosarcoma, haemangiosarcoma, osteosarcoma, soft tissue sarcoma.
4. Infiltrative lipoma / liposarcoma, leiomyosarcoma, malignant nerve sheath tumours (neurofibrosarcoma).

Question 5

1. Examples of common benign round cell tumours.
2. Examples of common malignant round cell tumours.
3. Examples of less common malignant round cell tumours.

Answer 5

1. Histiocytoma, plasmacytoma, melanocytoma.
2. MCT, lymphosarcoma, melanoma.
3. Multiple myeloma, malignant histiocytosis.

Question 6

1. Are cure rates better for first surgery or second?
2. What are the determining factors for what the ideal margins are for tumour excision?
3. Which organ can be removed in its entirety to achieve aggressive margins?

Answer 6

1. First.
2. Tumour type, grade, tissue type, anatomical position.
3. Spleen.

Question 7

What associated tissue should be included in the margins?

Answer 7

Skin – determine if skin affected or if tumour subcutaneous.
Subcutaneous tissues – tumours run through these.
Fat – Tumours run through this.
Fascia – collagenous CT act as barrier to tumours.
Muscle – usually protected by a layer of fascia.

Question 8

Morbidity risk.

Answer 8

• Healing e.g. high tension = high risk, of breakdown.
• Function post-operatively e.g. amputation.
• Clearcut case example – large aggressive mass on lower limb –> amputation over local surgery unlikely to close / heal w/o tissue.
• Not so clearcut case example – large benign mass on lower limb –> risk local surgery with risk of wound breakdown over amputation?

Question 9

1. Debulking of macroscopic vs microscopic tumours.
2. Debulking tumours for palliation.

Answer 9

1. Cut away some or all of macroscopic tumour.
   Remove macroscopic tumour with knowledge that there is local and/or distant microscopic tumour tissue.
2. E.g. ulcerated masses where possible to get the skin to heal w/o aiming for cure.
   E.g. large masses affecting ability to walk due to pressure on joints or muscles.
   e.g. long bone osteosarcoma = amputation reduces cancer-associated pain.
   E.g. Anal sac adenocarcinoma with paraneoplastic syndrome of hypercalcaemia and local LN spread.

Question 10

What factors are used to prognosticate for tumours?

Answer 10

Tissue of origin (cell types).
Behaviour.
Location.

Question 11

Give some surgical resection options.

Answer 11

• Intracapsular / debulking.
• Marginal excision.
• Wide excision.
• Radical ‘en bloc’ excision.
• Inoperable?

Question 12

Intracapsular resection.
1. Intent?
2. Method?

Answer 12

1. Should be conscious decision rather than accident through failure to remove enough tissue when attempting to cure.
2. Incise over and then through tumour and then remove in chunks, leaving macroscopic tumour behind.

Question 13

Marginal excision…
1. What is it?
2. Downfall?
3. Classic tumour w/ ‘pseudo-capsule’.
4. When is this usually performed?
5. When may excisional biopsies be appropriate?

Answer 13

1. Removal just outside or through the periphery of the tumour.
2. Tumour could have a ‘pseudo-capsule’ and a marginal excision cuts through this, often leaving microscopic disease behind.
3. Soft tissue sarcoma, which often palpates similar to a lipoma.
4. In cases where locations makes surgery tricky and money is tight / pre-op biopsy not possible. Client communication v important so they understand limitations of this approach and potential effect on the outcome.
5. LNs, small cutaneous nodules w/ plentiful skin, mammary gland tumours in dogs, CNS tumours for decompression, exploratory surgery that finds a mass where a repeat surgery is less likely.

Question 14

Wide excision…
1. What is it?
2. What does this technique assume?

Answer 14

1. Common technique where a margin of normal tissue is removed and surgical plane does not go near the actual tumour.
2. That the tumour will not invade the underlying fascia.

Question 15

Radical excision…
1. What is it?
2. When is this inappropriate? – exception?
3. Head and neck radical excisions?
4. Limb/body radical excisions?
5. Abdominal radical excisions?

Answer 15

1. Compartmental removal, removing a compartment where a tumour is located.
2. Most skin tumours – except for skin on pinna.
3. Enucleation, maxillectomy / mandibulectomy.
4. Amputation, chest wall / body wall resection.
5. Splenectomy, nephrectomy.

Question 16

Factors for consideration before planning surgery.

Answer 16

Diagnosis.
Surgical options.
Complications.
Healing.
Owner wishes.
Patient factors.

Question 17

Diagnosis as a consideration factor before surgical planning.

Answer 17

Determines the margins needed based on EBVM (ever changing).
- Type.
- Grade.
- Stage.

Question 18

Surgical options as a consideration before surgical planning.

Answer 18

• Location / size of mass.
• Technique e.g. marginal vs wide.
• Orientation of incision.

Question 19

Complications as a consideration factor before planning surgery.

Answer 19

• Tumour specific complications: intraoperative or postoperative.
• Tension e.g. might need tension-relieving techniques.
• Dead space e.g. might need a drain to avoid post-op seroma.

Question 20

Healing as a consideration factor before planning surgery.

Answer 20

• Site / tension or movement e.g. mass on lower leg, or over a joint.
• Tumour / known to heal poorly e.g. MCT.
• Patient factor / immunosuppressed e.g. exogenous or endogenous steroid (Cushings).
• Patient factors e.g. young and lively vs calm and sedate.

Question 21

Owner wishes as a consideration factor before planning surgery.

Answer 21

Cure vs debulk – manage expectations.

Question 22

Patient factors as a consideration before planning surgery.

Answer 22

• Co-morbidities / risk of delayed healing.
• Temperament / risk of wound interference / issues with healing.

Question 23

1. Margin recommended for carcinoma – why?
2. Sarcomas recommended margin – why?
3. Round cell tumour recommended margin.
4. Grade and margin requirement relationship.

Answer 23

1. > 1cm – metastasis more important than local invasion.
2. > 3cm – local invasion more important than distant metastasis.
3. 1-3cm.
4. Higher grade, higher margin.

Question 24

Examples of how tumour location affects aggression of tumours.

Answer 24

MCT on prepuce or digits.
Axial (non-limb) osteosarcoma.
Oral squamous cell carcinoma very locally aggressive but slow to metastasise.

Question 25

How can taking too small margins be avoided in surgery.

Answer 25

Using ruler and marker to map out sites of excision as everything will move / shrink when cutting starts.

Question 26

How much of a sample can be given for histopathology?

Answer 26

• All of the tumour or a representative sample.
• should involve an edge.
• Tissue cannot be assessed until fixed.
• IDEXX 10% formalin, 10mm cube if need rapid result.

Question 27

How can you indicate margins to histopath and what is described as clean/dirty margins?

Answer 27

Ink your margins.
Dirty = abnormal cells right up to margin.
Clean = abnormal cell away from incised margin, and distance measured in mm.

Question 28

How can margin orientation be indicated to histopath and why is it important to do this?

Answer 28

Typically with suture.
Mark top / bottom / left / right.
Histopath can only tell you orientation if you have marked it.
Important to know margin orientation in case need to plan second surgery for residual tissue based on uneven margins.

Question 29

Options for incomplete margins.

Answer 29

Second surgery – may be less successful than a successful primary surgery but offers better chance of cure than adjunctive therapy. Closure may be even more difficult second time around.
Adjunctive therapy – radiation / chemo.
Wait and see if recurs – can be risky and requires sig. client comms. Is one of main reasons to have staged appropriately first before planning definitive excision.

Question 30

How do we mitigate causing malignancy during surgery?

Answer 30

• Kit – one kit to excise and new kit to close.
• New gloves for closure.
• Re-drape or new over-drape.
• Drains: -
  – Avoid unless absolutely necessary due to increased risk of infection.
  – Better to close w/ sutures.
  – If re-operate, must include drain exit point in second surgery due to risk of tumour spread in first surgery.

Question 31

1. How is the orientation of the incision decided?
2. Options of incision shapes.

Answer 31

1. Based on tension lines of the individual patient to reduce tension along the suture line.
2. • Linear – used where there is no skin to be removed i.e. subcutaneous masses e.g. small-medium subcutaneous benign masses not causing skin stretching e.g. lipoma.
     - Elliptical – skin to be removed e.g. cutaneous masses or large subcutaneous masses where dead space would be an issue due to skin stretching.

Question 32

Incision length for best result.

Answer 32

1:3 width : length ratio.
– Subcutaneous mass may only need incision big enough to ‘shell out’.
– Ratio achieves neat finish w/o dog ears.

Question 33

1. How are lateral margins chosen?
2. How are deep margins chosen?
3. Should electrosurgery be used during mass removal?

Answer 33

1. Based on tumour type.
2. • Based on tumour type and grade.
     - One fascial plane adequate for most skin masses.
     - 2 fascial planes for fibro-sarcomas.
     - No need to close fascia.
3. Ideally not until tumour has been excised to avoid making it more difficult to assess histological margins due to tissue changes caused by cautery.

Question 34

Consideration factors for surgical site closure under tension.

Answer 34

• Compromise to circulation.
• Wound healing.
• Suture complications.
• Wound distortion.

Question 35

Circulatory compromise as a factor for closure under tension.

Answer 35

Compromise to arteries can cause ischaemia.
Compromise to veins can cause oedema.

Question 36

1. Wound healing as a factor of closure under tension.
2. Suture complications as a factor of closure under tension.
3. Wound distortion as a factor of closure under tension.

Answer 36

1. Can get dehiscence and/or necrosis.
2. Patient interference.
   Cheese-wiring / cut out.
3. Distortion of anatomic areas such as anus or eyelid.

Question 36

Examples of tension-relieving techniques.

Answer 36

• Undermining.
• Multiple layer closure.
• Tension-relieving sutures.
• Releasing incisions.
• Non-linear closure.

Question 37

1. Undermining.
2. Closure of multiple layers.

Answer 37

1. Releases elasticity of the skin immediately around surgical site so skin can be advanced into place and avoid tension during closure. Must not disrupt subdermal blood supply.
2. Spreads tension from deep to shallow so level of the skin is tension-free.
   Care w/ closing down tissue planes that normally move across each other during motion.

Question 38

1. Tension-relieving suture patterns.
2. Releasing incisions.

Answer 38

1. Subcutaneous to be prioritised e.g. walking sutures.
   Cutaneous to be avoided e.g. vertical mattress sutures, near-far-far-near sutures.
2. Best avoided where possible BUT very useful, particularly on lower limb where skin is in short supply.

Question 39

Non-linear closures.

Answer 39

• Allow closure by using skin further from the surgical site.
• Subdermal plexus flap.
• Axial pattern flaps.
• Free skin grafts.

Question 40

1. Where are free skin grafts useful?
2. Second intention healing.

Answer 40

1. Distal limb defects.
2. Can be used successfully in correctly selected patients.
   Can be painful and expensive.
   Can lead to non-healing wounds.
   Can lead to contractures which then require revision.

Question 41

1. MCTs more common in dogs or cat?
2. Breeds that have MCTs most commonly?
3. More commonly singular or multiple?

Answer 41

1. Dogs.
2. Brachycephalics, boxers, Bostons, bulldogs, Labradors.
3. Singular – 10-20% cases of multiples.
   Multiples unlikely to be secondary spread within skin.

Question 42

1. MCTs more commonly visceral or skin?
2. Where else also possibly found?
3. Cutaneous sites with higher risk of malignancy.

Answer 42

1. Skin.
2. GIT, spleen, liver, bone marrow. Often highly malignant if visceral.
3. Perineal, nail beds, preputial.

Question 43

1. Are non-visceral MCTs more commonly subcutaneous or intradermal?
   – Which of these has the higher potential of malignancy?
2. What are the 2 scoring systems for grading MCTs?

Answer 43

1. Intradermal. – intradermal.
2. Patneik: I, II, III, IV.
   Kuipel: Low or high. (low more common).

Question 44

1. What is the preferable treatment of choice for MCT treatment?
2. What are medical options chosen on the basis of?

Answer 44

1. Surgery (70-80% can be cured by surgery alone).
2. Patient constraint.
   Owner preference.
   Financial constraints.
   Vet preference / surgical confidence.

Question 45

1. Flag system for MCT growth.
2. Flag system for MCT appearance.

Answer 45

1. Green = slow growth.
   Orange = changing size (smaller and larger again).
   Red flag = rapid or recent growth.
2. Distinct = green and orange.
   Indistinct = red flag.

Question 46

Flag system for histamine release.

Answer 46

Green flag = inactive, no sign of histamine release, no redness, patient ignoring mass.
Orange flag = intermittently changing in size.
Red flag = Local inflammation: Darier’s sign, oedema.
Systemic effects: Hives / pruritis; anaphylaxis; GI ulceration.

Question 47

1. Sample method for MCT. – how does the tumour type facilitate this? – Risk? — mitigation.
2. Histopathology considerations.

Answer 47

1. FNA – exfoliates easily – high grade MCTs are risky — consider pre-treatment w/ anti-histamines.
2. Consider incisional biopsy before definitive surgery for MCTs w/ red flags, high risk breeds, high risk anatomical areas.

Question 48

1. MCT metastasis.
2. Prognostic panel for MCT.

Answer 48

1. Local mets to local LNs, still be suspicious even if normal size.
   Distant mets to liver and spleen.
2. Some labs offer additional testing incl. Ki67 immunohistochemistry and c-KIT.
   Histopathology not always helpful to predict post-surgical prognosis.
   May help decision making m=fir dirty margins and masses sitting in the grey area between benign and malignant.

Question 49

1. Minimum lateral margin.
2. Fascial planes.
3. Higher grade?

Answer 49

1. 2cm.
2. One deep fascial plane.
3. Larger and deeper margins for higher grade.

Question 50

MCT medical treatment as an adjunct to surgery.

Answer 50

• Before surgery to shrink the mass to make surgery ‘easier’. Brings its own challenges.
• After surgery as incomplete removal so medical treatment to reduce risk of recurrence and/or to treat cases with pre-existing mets or w/ high risk of mets.
• Drug therapy
  – Chemo = vinblastine.
  – Tyrosine kinase inhibitors e.g. Palladia / Masivet.
  – Stelfonta = drug that in injected into small population of MCTs and cause cell death.

Question 51

1. Medical treatment of MCT as alternative to surgery.
2. Medical palliative treatment of MCT.

Answer 51

1. • When mets present.
     - When surgery considered inappropriate due to grade / location / patient / owner.
     - Options include drug therapy, radio therapy.
2. When other treatment options are discounted.
   - Anti-histamines.
   - Steroids.