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FRCS Plastic Surgery > KEY NOTES CHAPTER 2: SKIN AND SOFT TISSUE LESIONS - Soft Tissue Tumours. > Flashcards

KEY NOTES CHAPTER 2: SKIN AND SOFT TISSUE LESIONS - Soft Tissue Tumours. Flashcards

0
Q

What are soft tissue tumours?

A

• ‘Soft tissue’ is defined as non-epithelial extraskeletal tissue:
∘ Muscle
∘ Fat
∘ Fibrous tissue
∘ Vessels.
• By convention, peripheral nerves are also defined as soft tissue.

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1
Q

How are soft tissue tumours broadly classified?

A
  • Benign
  • Malignant
  • Tumours of intermediate malignancy.
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2
Q

What types of benign soft tissue tumours are there?

A 
• Resemble normal tissue:
∘ Lipoma.
∘ Leiomyoma.
∘ Rhabdomyoma.
∘ Lymphangioma.
∘ Schwannoma.
• Limited capacity for autonomous growth.
• Not locally invasive; low rate of recurrence following treatment.
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3
Q

What are malignant soft tissue tumours?

A
  • Known as sarcomas.
  • Locally invasive; can metastasise.
  • Prone to recurrence; require radical treatment.
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4
Q

What are tumours of intermediate malignancy? Give some examples.

A

• These are tumours of borderline or low malignant potential.
• May have high local recurrence rate but low risk of metastasis.
• Examples:
∘ Dermatofibrosarcoma protuberans (DFSP)
∘ Kaposiform haemangioendothelioma
∘ Atypical lipoma
∘ Haemangiopericytoma.

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5
Q

What is the definition of sarcoma?

A
  • ‘Sarcoma’ = Greek meaning ‘fleshy growth’.
  • Mesoderm derived malignancies e.g. bone and muscle = sarcomas.
  • Epithelial tissue malignancies = carcinomas.

• Peripheral nerve malignancies although of ectodermal origin, are also considered sarcomas.

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6
Q

What is the epidemiology of sarcomas?

A
  • 1% of all malignant tumours; ~20/million/year.
  • Soft tissue sarcomas (STSs) increase in incidence with age.
  • Bone sarcomas have bimodal incidence.
  • 75% of STSs are in lower limb (thigh). Other sites: trunk, retroperitoneum, viscera, H&N.
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7
Q

What is the aetiology of sarcomas?

A

Sporadic (majority).

Potential causative factors:
∘ Genetic
(a) NF-1: up to 10% lifetime risk of malignant transformation (MPNST: malignant peripheral nerve sheath tumours).
(b) Gardner syndrome (familial polyposis coli) –> desmoid tumours.
(c) Hereditary retinoblastoma survivors –> STS.
(d) Gorlin’s syndrome –> fibrosarcoma and rhabdomyosarcoma.
(e) Li Fraumeni syndrome (germline mutation in p53) –> STS.

∘ Radiation (e.g. breast) –> angiosarcoma (16-fold) & STS (2-fold increase)
∘ Chronic lymphoedema –> lymphangiosarcoma.
∘ Chronic burn scar.
∘ Chemical exposure: phenoxyacetic herbicides, Agent Orange, arsenic.
∘ Viral infection: herpes virus or HIV –> Kaposi sarcoma; Epstein-Barr virus (EBV) –> smooth muscle sarcoma.

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8
Q

How do sarcomas present?

A
  • Typically presentation: painless lump.
  • Other symptoms depend on location and structures distorted by tumour.

Features

  1. Size >5 cm
  2. Deep to deep fascia
  3. Pain
  4. Increasing size.

1 feature - 16%; 2 - 43%; 3 - 65%; 4 - 86% chance of sarcoma.

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9
Q

What is the diagnostic pathway for sarcomas?

A
  1. Clinical assessment
  2. Radiological assessment
  3. Biopsy
  4. Planning
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10
Q

What is the appropriate management for suspected sarcomas?

A
  • Suspected sarcomas –> urgent specialist sarcoma MDT referral –> imaging, biopsy and treatment.
  • Do not attempt biopsy / treatment outside SSMDT results in inadequate surgery and treatment delay.
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11
Q

What is covered in the clinical assessment?

A

∘ Extent of resection
∘ Regional lymphadenopathy (rare in sarcoma)
∘ Reconstruction required.

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12
Q

What is the purposes of different radiological assessments and how should they be ordered?

A

∘ Imaging usually done before biopsy to minimise artefact from bleeding or oedema.
∘ Localises and characterises tumour.
∘ Stages the disease.

  1. CT: assesses primary tumour and any metastatic disease.
  2. MRI: differentiates fat and nonfat tumours (soft tissue detail).
  3. PET: sensitive for most sarcomas.
  4. USS: targeted biopsy.
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13
Q

What different biopsies may be performed?

A
  1. Gold standard = percutaneous core biopsy, reviewed by specialist sarcoma histopathologist.
    - Ultrasound or CT guidance: target areas of interest within tumour. Also helps avoid passing through uninvolved muscle compartments.
  2. Open biopsy (if core biopsy failed): this transgresses compartment boundaries and may upstage tumour.

Biopsies, incisions and drain sites are placed within the zone of future excision.

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14
Q

How is treatment planned after 1,2,3?

A

∘ Neoadjuvant and adjuvant therapies.

∘ Surgery and reconstruction.

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15
Q

How are sarcomas classified?

A

∘ Histological type
∘ TNMG classification
∘ Stage.

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16
Q

Name some different histological types of sarcomas.

A

Too many! Few e.g.s

∘ Smooth muscle - leiomyosarcoma
∘ Striated muscle - rhabdomyosarcoma
∘ Fat - liposarcoma
∘ Blood and lymph vessels - angiosarcoma, Kaposi sarcoma
∘ Fibrous tissue - malignant fibrous histiocytoma (MFH)
∘ Nerve - malignant peripheral nerve sheath tumour (MPNST)
∘ Synovium - synovial sarcoma
∘ Skin - atypical fibroxanthoma (AFX).

  • Most common sarcomas in UK:
  • MFH (28%),
  • Liposarcoma (15%),
  • Leiomyosarcoma (12%).
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17
Q

What is the TNMG classification of sarcomas?

T

A 
Primary tumour (T)
• Tx: Cannot be assessed
• T0: No evidence of primary tumour
• T1: Tumour ≤5 cm
 ∘ a: Superficial
 ∘ b: Deep
• T2: Tumour >5 cm
 ∘ a: Superficial
 ∘ b: Deep

(Superficial tumour = superficial to fascia).

18
Q

What is the TNMG classification of sarcomas?

N

A

Regional lymph nodes:
• Nx: Cannot be assessed.
• N0: No mets.
• N1: RLN metastasis.

19
Q

What is the TNMG classification of sarcomas?

M

A

Distant metastasis (M)
• M0: No distant metastasis
• M1: Distant metastasis.

20
Q

What is the TNMG classification of sarcomas?

G

A 
Trojani grade (G)
• Based on number of mitoses, presence of necrosis, degree of differentiation.
• G1: low-grade tumour
• G2: intermediate-grade tumour
• G3: high-grade tumour.
21
Q

What is the clinical staging for sarcomas?

A

.

22
Q

What is the Enneking Classification for benign sarcomas?

A

.

23
Q

What is the Enneking Classification for malignant sarcomas?

A

.

24
Q

What are the 2 main systems used to plan excision margins?

A
  1. AJCC residual tumour classification

2. Enneking classification

25
Q

What factors are taken into account when planning sarcoma excisions?

A

Typical behaviour of sarcoma:
• Most have centrifugal growth pattern.
• Compression of surrounding soft tissue produces ‘pseudocapsule’, a reactive zone around the tumour, harbouring nests of tumour cells.
• Non-specialists may find sarcoma shells out easily, but this inevitably leaves viable tumour cells within pseudocapsule.
• Sarcomas usually respect fascial boundaries until late in their progression.

26
Q

What is the AJCC residual tumour (R) classification?

A
  • Describes tumour status following treatment.
  • Includes lymph nodes and sites of distant metastases.
    • R0 - no residual tumour
    • R1 - microscopic residual tumour
    • R2 - macroscopic residual tumour.
27
Q

How is the Enneking classification used to plan excision margins?

A
  • Enneking classification correlates the tumour stage with the recommended excision margins depending on whether mass is benign or malignant.
  • Based on stage, the appropriate surgical margin is chosen to obtain local control.
28
Q

What are the 4 main types of sarcoma excision according to margins?

A
  1. Intralesional
    • ‘Shell out’ procedure.
    • Macroscopic tumour is left behind; recurrence ~ 100%.
  2. Marginal
    • Pseudocapsule forms periphery of resection specimen.
    • Microscopic disease is left within reactive zone; recurrence is 40-60%.
  3. Wide
    • Removes tumour and pseudocapsule with a margin of nonreactive normal tissue.
    • Risks leaving microscopic skip lesions; more likely with high-grade lesions.
    • Recurrence rates ~ 10%.
  4. Radical
    • Removes all normal tissue of involved compartment.
    • Muscles are excised en bloc, from origin to insertion, including fascial sheaths.
    • In theory, leaves no residual disease; local recurrence rate 0.5%.
30
Q

What specific sarcomas do not follow the above management pathway?

A

Chemosensitive tumours
• Paediatric rhabdomyosarcoma,
• Soft tissue Ewing’s sarcoma
• Synovial sarcoma

Treatment
∘ Neoadjuvant chemotherapy
∘ Surgery,+/- radiotherapy
∘ Further adjuvant chemotherapy.

30
Q

What is the argument between amputation vs limb salvage?

A
  • Amputation considered when critical structures must be resected, which would otherwise leave a poorly functioning limb.
  • Limb salvage strategies have reduced amputation rates to ~ 5%.

• To achieve low recurrence with limb salvage:

  1. Neoadjuvant radiotherapy or, less commonly, chemotherapy
  2. Resection: aim for wide margin while preserving critical neurovascular structures.
  3. Reconstruction: functional recon with nerve grafts, nerve transfers, vascular reconstruction and free functioning muscle transfer.
  4. Adjuvant radiotherapy or, less commonly, chemotherapy.
31
Q

What is the prognosis for sarcomas?

A

• Overall survival 50-60%.
• Prognostic factors: age, metastasis at presentation, tumour size and depth.
• Trojani histological grade is critical determinant of prognosis:
1. Low grade: 90% 5-year survival.
2&3. High grade: 50-60% 5-year survival M0;

32
Q

What is different about sarcoma in children compared with adults?

A
  • Children with metastatic disease, fare better than adults.
  • Radiotherapy has greater risk of long-term sequelae.
  • Chemotherapy may cause infertility.
33
Q

What is the role of isolated limb perfusion?

A

• Controversial treatment for unresectable extremity sarcoma.

Uses:
• Neoadjuvant: reduce extent of extremity sarcoma to try to avoid amputation.
• For extensive locoregional metastases.

34
Q

What are the 4 main types of cutaneous sarcomas?

A
  • Primary tumours originate in skin; managed similar to other skin cancer; imaging rarely required if no evidence of metastasis.
  • Secondary tumours are skin metastases from cutaneous or noncutaneous sarcomas.
  1. MFH
  2. AFX
  3. AS
  4. DFSP
36
Q

What is malignant fibrous histiocytoma?

A
  • Aka pleomorphic undifferentiated sarcoma.
  • Rare aggressive tumour; presents as a firm subcutaneous nodule in elderly.
  • Commonly affects thigh, upper limb and retroperitoneum.
  • 2∕3 located in skeletal muscle;
36
Q

What is angiosarcoma?

A
  • Aggressive, multicentric tumour; typically on face and scalp of elderly.
  • At presentation, it usually extends beyond its clinical margins.
  • High rate of local recurrence and metastasis.
  • Surgical margins 5 cm, where possible.
37
Q

What is atypical fibroxanthoma?

A
  • Aka pleomorphic undifferentiated sarcoma of skin.
  • Superficial cutaneous counterpart of MFH.
  • Presents as small, firm cutaneous nodules.
  • Usually on head and neck of elderly, in sun-damaged or irradiated skin.
  • Histology is indistinguishable from MFH - aggressive, poorly differentiated lesion.
  • Prognosis usually excellent (unlike MFH).
  • AFX rarely recurs WLE & clear margins.
38
Q

What is dermatofibrosarcoma protuberans (DFSP)?

A
  • A tumour of intermediate malignancy (prone to local recurrence but rarely metastasises).
  • Slow-growing, red-brown nodule, most common on the trunk.
  • Mean age ~ 35 years.
  • Pathogenesis involves a distinctive rearrangement of chromosomes 17 and 22.
  • Excised with wide margin (>2-3 cm) down to deep fascia: local recurrence rates ~ 15%.
  • Mohs LRR ~ 1.3%.
  • Imatinib (tyrosine kinase inhibitor): neoadjuvant treatment for inoperable, metastatic or recurrent DFSP.
39
Q

What is the incidence of bone sarcoma?

A

~500 yr in UK

40
Q

What are the most common types of bone sarcoma?

A

∘ Osteosarcoma
∘ Ewing’s sarcoma
∘ Chondrosarcoma.

41
Q

What is the management for bone sarcoma?

A

• Investigated and managed in specialist bone sarcoma centres.

Treatment:

  1. Neoadjuvant therapy (chemotherapy±radiotherapy)
  2. Surgical resection and reconstruction
  3. Postoperative adjuvant therapy, determined by surgical margins and histology.
42
Q

…

A

Reconstruction of long bones:
∘ Bespoke prostheses
∘ Allograft bone
∘ Extracorporeal radiotherapy.
- Involved bone is resected.
- Tumour is excised from bone after removal from patient.
- Remaining bone is irradiated to 90 cGy (which avoids collateral soft tissue damage) and reinserted as graft.

Capanna technique:
• Augmenting vascularity with
free vascularised bone from fibula, inserted into diaphysis of irradiated long bone after reaming.

43
Q

What are the objectives of any cancer staging tool?

A

(1) to aid in planning the course of treatment,
(2) to provide insight into the prognosis,
(3) to assist in evaluating the results of treatment,
(4) to facilitate effective interinstitutional communication, and
(5) to contribute to continuing investigation of human malignancies.

FRCS Plastic Surgery (63 decks)

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