Sarcoma

Question 1

What is sarcoma?

Answer 1

Sarcoma is a malignant tumour of mesodermal origin
More than 50 types - broadly divided into soft tissue and bony sarcomas
Cell of origin is usually unknown but differentiate to resemble a particular tissue type from which they are named.
Rare - approx 1% of adult cancers (15% of childhood cancers)
Soft tissue sarcomas are more common than bone
Equal sex distribution
Most commonly affect lower limb (~50%) - followed by upper limb, trunk, H&N. Also intra/retro peritoneal sarcomas
Most often arise spontaneously
May be associated with no of. risk factors
- Genetic e.g Li Fraumeni, NF1, Familial retinoblastoma, Gorlin syndrome, Gardeners syndrome
- Environment - chemical agents e.g arsenic, vinyl chloride
- Iatrogenic - previous radiotherapy, breast cancer - lymphoedema
- Infection - HIV (Kaposis), EBV (leiomyosarcoma)

Question 2

What are the common differential diagnoses for soft tissue lumps in adults?

Answer 2

Benign v Malignant

Benign

• lipoma
• sebaceous cyst (epidermis cyst)
• schwanoma
• vascular malformation
• hand tumours

Malignant
- cutaneous metastasis

Question 3

What are the common differential diagnoses for soft tissue lumps in children?

Answer 3

Benign v Malignant

Benign
Vascular anomalies
Dermoid
Cysts
Pilomatrixoma

Malignant

Question 4

Pt presents with a large lump on leg - how do I approach this pt?

Answer 4

This patient is likely to require triple assessment of this lump

Firstly I would take a directed history and examination to elicit nature of lump
Aim to establish if this is benign v malignant lump

Pertinent features which would make me concerned re malignancy i.e sarcoma are:

• enlarging mass
• pain
• size >5cm
• deep to fascia

I would also want to know about sensory alterations/symptoms

Also want to understand if any risk factors

• Genetic e.g Li Fraumeni, NF1, Familial retinoblastoma, Gorlin syndrome, Gardeners syndrome
• Environment - chemical agents e.g arsenic, vinyl chloride
• Iatrogenic - previous radiotherapy, breast cancer - lymphoedema
• Infection - HIV (Kaposis), EBV (leiomyosarcoma)

+ PMH/medications to understand general fitness for surgery and lifestyle factors which may influence my management

On exam - apart from size and relation to fascia also want to test for mobility (1 v 2 planes) and Tinels sign which would make me think specifically about nerve sheath tumours

I would also want to assess LN basins though I know most sarcomas spread via haematogenous route
Exceptions are:
Synovial
Epitheloid
Clear cell
Rhabdomyosarcoma

Thinking ahead towards possible excision I would also need to asses the pt re possible reconstructive options

This pt then requires imaging and percutaneous core biopsy to localise/characterise the tumour and confirm my clinical diagnosis

However if this is clinically sarcoma - pt needs to be managed within specialist sarcoma MDT to ensure imaging reported by specialist MSk radiologists and biopsy is performed appropriately in such a way that the biopsy tract can be excised at the time of definitive excision and to avoid “whoops procedures”

First instance - most practical to do USS +/- guided core biopsy at same time for diagnosis

Usually then require MRI to delineate anatomy & aid surgical planning
T1 - fat white / tumour grey
T2 - tumour white
+/- gadolinium enhancement

Then require staging CT

Question 5

Tell me about the histological features of soft tissue sarcoma?

Answer 5

Pathological diagnosis relies on morphology and immunohistochemistry

The most important prognostic factor is the Trojani grade which is based on semi quantitative assessment of:

• cellularity
• mitotic counts
• differentiation/ plea orphan
• areas of necrosis

Trojani grade:
1 - well differentiated, no necrosis, 50% necrosis, >20 mitoses

Question 6

What are the factors affecting prognosis in soft tissue sarcoma?

Answer 6

Overall survival is ~50% in soft tissue sarcoma
Prognosis depends on:
- Age
- large tumour size/depth at presentation
- Trojani grade
- Stage and evidence of metastatic spread at presentation

Question 7

What is Dercums disease?

Answer 7

Rare disease - unknown aetiology
Typically females (often post menopausal)
Often assoc with obesity
Characterised by multiple painful lipomas esp trunk
Progressive
May require excision of symptomatic/troublesome lipomas.