Soft Tissue Tumours

Benign

AV Malformations

 

AVM and sclerotherapy0002AVM and sclerotherapy0001

 

Elasto Fibroma Dorsi

Condition

 

Strange scapular tumour

- typically bilateral 

- occurs in lat dorsi

 

Complain of lump which appears around scapula

 

Imaging

 

Looks like muscle on CT

 

Behaviour

 

Benign

 

Histology

 

Shows marked amount of elastin

 

 

 

Fibromatosis

Aggressive Fibromatosis / Desmoid Tumour

 

Benign aggressive 

- most serious of all benign STT

 

Types

 

1.  Intra-abdominal 

- association familial polyposis coli & Gardner's syndrome

- aggressive infiltration

- death from retroperitoneal extension

 

2.  Extra-abdominal 

 

Non-metatasizing locally aggressive STT

- often invasive locally

- similar to low grade fibrosarcoma

 

Classically arise chest wall

- also limbs, head & neck

 

2 types

- superficial fibromatosis - palmar & plantar

- deep fibromatosis

 

Epidemiology

 

F > M 

Average age 40 years

 

Presentation

 

Mass most common

Stiff joint

Neurological compression

Mostly proximal - axilla & groin

 

Pathology

 

Gross

 

Firm mass with white hard cut surface

- may infiltrate local muscle

 

Histology

 

Spindle shaped fibroblasts with plump nuclei & mildly eosinophilic cytoplasm

- often arranged in parallel rows

- separated by variable but large amount of collagen

- may have high degree of cellularity

- very few mitoses & no necrosis

 

Can infiltrate skeletal muscle at periphery

 

Management

 

Wide resection + DXRT

 

80% success

 

Recurrence

 

Intralesional excision 

- 90% recurrence

 

Wide excision 

- 50% recurrence

 

Tumour resection margin

- best prognosticator

- tumour margin clear > 2 mm

 

Radiotherapy alone 

- used for inoperable tumours & after debulking 

 

 

 

Ganglion

Definition

 

Cystic structure lined by a mature capsule of dense fibrous tissue

- contains thick viscous fluid with a high mucopolysaccharide content

- fluid is a myxoid degeneration of synovial fluid

 

Epidemiology

 

Most common in young females

- peak age 15-30

- F:M = 3:1

 

Most common tumour in hand (2/3)

 

Aetiology

 

Unclear

 

Numerous theories

- synovial herniation through capsular defect with development one way valve

- synovial rest

 

Pathology

 

Development

- in early stages, communicate with cavity of tendon or joint

- with time, connection obliterated by fibrous tissue

- become completely enclosed

- fluid becomes inspissated (thickened / dried)

 

Gross

- thin-walled cyst

- may be multiloculated

- easily separated from surrounding soft tissues

- contents clear, viscous & jelly-like

- arthrogram usually demonstrates joint communication

 

Histology 

- wall of paucicellular fibrous connective tissue

- no true epithelial or synovial lining

- contents consist of hyaluronic acid / plasma proteins

 

History

 

Most commonly present with cosmesis issue

 

Appears suddenly or develop slowly

 

Subside with rest & enlarge with activity

 

Location

 

Most common around hands & feet

 

Increased incidence with

- RA

- OA (eg Meniscal cyst)

 

Management 

 

Non-operative

 

Aspiration of cyst

 

Rupture of wall with multiple needle punctures

- instillation of xylocaine & celestone

- 50% recurrence

 

Operative

 

Excision

 

Ankle ganglionFoot Ganglion Excision

 

GA & tourniquet

- excision of lump in full

- attempt to locate and tie off neck

- may excise segment of capsule

 

 

 

Lipoma

Definition

 

Benign adipose tumour

 

Epidemiology

 

Most common mesenchymal neoplasm

- arise from normal fat

- appears during adulthood

 

Clinical

 

80% subcutaneous

- shoulder girdle & proximal thigh most common sites

- well circumscribed mobile, round masse

 

Condition

 

Durcen's Disease 

- multiple lipoma subcutaneous disease

 

MRI

 

Same signal intensity as surrounding fat

 

Lipoma Thigh MRI

 

Classification

 

Divided into 5 subtypes 

 

1.  Simple lipoma

2.  Spindle Cell Lipoma

3.  Pleomorphic Lipoma

4.  Intramuscular & Intermuscular

5.  Angiolipoma

 

1.  Simple Lipoma

 

Incidence

- most common mesenchymal tumour

- tumour of adulthood usually > 40

- multiple in 5%

- 80% of all lipomas

- shoulder & proximal thigh common site

 

Macroscopic

- well circumscribed

- round to ovoid masses

- 4-10cm long

- homogenous pale to bright yellow on cut surface

 

Microscopic

- same as normal fat

- sheets of mature fat cells ovoid to round in shape

- contain single fat droplet 

- peripheral nucleus 

- capillary like vessels are occasionally seen between lobules

- areas of myxoid change or dense fibrous trabeculae are sometimes seen

 

2.  Spindle Cell 

 

Painless firm nodule on neck & shoulder in middle aged men

 

Macroscopic

- encapsulated with a delicate fibrous membrane

- arise within the subcutaneous tissue

- on section may have white to grey myxoid areas

 

Microscopic

- mature fat cells

- variable number of benign spindle cells

- the spindle cells are uniform & arranged in parallel

- mitotic figures are rare

- occasional lipoblasts occur

 

3.  Pleomorphic Lipoma

 

Rare

 

Microscopic

- similar to spindle cell

- has pleomorphic fat cells 

- multinucleated giant cells instead of spindle cells 

 

4,  Intra & Inter Muscular Lipoma

 

Lipoma Intramuscular0001Lipoma Intramuscular0002

 

Macroscopic

 

2 types

- well defined fatty tumour or

- ill defined infiltrative lesion

- unlike superficial lipomas these variants often don't have a capsule

- tend to encircle nerves

 

Lipoma MRI 1Lipoma MRI 2Lipoma MRI 3

 

Lipoma Clinical 1Lipoma Clinical Photo 2

 

Microscopic

- characterized by sheets & nests of mature adipose tissue insinuating between bundles of muscle fibres

- the fat cells are not atypical, & lipoblasts never occur

 

5.  Angiolipoma

 

Angiolipoma MRI0001Angiolipoma MRI0002

 

Atypical Lipoma

 

Microscopic

- have areas of fibrous, myxoid or other connective tissues

- often see secondary changes of calcification & haemorrhage etc

- true lipoma never becomes malignant

 

An atypical lipoma can't be differentiated from well differentiated liposarcoma

- often become large & mimic soft tissue sarcomas

 

Treatment

 

Wide margin

- clinical setting & an adequate tissue sample are required to differentiate liposarcoma

 

 

 

Neurilemmoma

Definition

 

Schwannoma

- benign tumour of nerve sheath

 

Epidemiology

 

Less common than neurofibroma

- occurs in adults

- can occur along any peripheral nerve

- also can occur along a nerve root

 

Usually a large nerve

 

More common in forearm

 

Seen in NF 2 

- acoustic Schwannoma

 

Gross Pathology

 

Usually located eccentrically within nerve 

- compared with NF which are fusiform swellings of the nerve

 

Well encapsulated

- capsule consists of epineurium

- bulges from originating fascicles & pushes aside adjacent fascicles

 

Histology

 

Contain spindled Schwann cells

 

Arranged in alternating hypercellular (Antoni A) & hypocellular (Antoni B) regions

 

Antoni A

- spindle cells form short intersecting fascicles

- whorling pattern with palisading nuclei

- nuclei pallisade & align into columns

- Verocay Bodies - adjacent parallel columns of nuclei separated by fibrillar cell processes

 

Antoni B

- spindle cells twisted & haphazardly arranged

- separated by abundant myxoid ground substance

- may be dilated blood vessels

- more loosely arranged myxoid tissue

 

Immunohistochemistry

 

Positive

- Vimentin

- S 100 strongly +ve

- Leu-7

 

Negative

- Glial fibrillary protein

- Keratin

 

Loss of genes on Chr 22

 

History

 

Painful tender lump

- altered sensation or weak uncommon

- usually along flexor surface

- can increase & decrease in size

 

Examination

 

Soft cystic lump

- mobile transversely but not longitudinally

- strongly positive Tinel's

 

MRI 

 

Show lesion on nerve periphery

 

Compared with NF which is in centre of nerve

 

Management

 

Operative excision

 

Usually removed easily

- open capsule & enucleate with little or no injury to nerve fascicles

- shelling pea from pod

 

If uncertain of diagnosis, obtain fresh frozen section

 

Malignant degeneration occurs, but rare

 

 

 

 

Neurofibroma

Definition

 

Benign tumour of nerve & sheath tissue

 

Epidemiology

 

Most common benign nerve sheath tumour

- associated with NF 1

- usually arises from small cutaneous nerves

 

Classification

 

1.  Localised

- most common type

- usually solitary (90%) with no genetic association

- nil malignant transormation

 

Originate from very small branches of cutaneous nerve

- non encapsulated

- consist of twisted spindle cells arranged in fascicles

- accompanied by wire-like bundles of collagen / myxoid stroma

 

2.  Diffuse

 

Uncommon

- proliferation of spindle cells, collagen & stroma

- permeates subcutaneous tissue & dermis

 

3.  Plexiform

 

Pathognomonic of NF 1

 

Massive expansion of nerve by proliferating tumour cells

- may involve small cutaneous nerve

- ill-defined nodule

- may originate in large nerve

- elephantiasis or gigantism

 

10% malignant transformation

 

Pathology

 

Contain proliferation of

- schwann cells

- perineural cells

- fibroblasts

 

Looks like bland but collagen rich fibrous tumour

- small to moderate amounts of mucoid material

- not encapsulated

 

S-100 stain

- far less intense than in neurilemmoma

 

DDx

 

Schwannomas / neurilemmoma

- contain only Schwann cells

 

Clinical

 

Localised - painless, soft, mobile

 

Diffuse - plaque-like cutaneous mass

 

Plexiform

- ropey redundant mass

- feels like a bag of worms

- 50% of NF patients develop malignancy

 

MRI

 

Diagnosis Neurofibromatosis type 1 (NF1) / Von Recklinghausen 

 

1.  Six or more café-au-lait spots (over 5mm in prepubertal individuals and over 15mm in postpubertal individuals)

2.  Two or more neurofibromas of any type or one plexiform neurofibroma

3.  Freckling in the axillary or inguinal region

4.  Optic glioma

5.  Two or more Lisch nodules (iris hamartomas)

6.  A distinctive osseous lesion such as sphenoid dysplasia or thinning of the long bone cortex with or without pseudarthrosis

7.  A first degree relative (parent, sibling, or offspring) with NF1 by the above criteria

 

Management

 

Localised

 

Surgical Indications

- pain

- nerve dysfunction

- rapid growth 

- suspicion of malignancy

 

Technique

- not easily separated from nerve

- excision usually involves partial resection of nerve

- if nerve small is sacrificed

- if nerve large and important need interposition graft

 

Plexiform 

 

Surgical Indications

- persistent symptoms / pain & numbness

- features of malignancy

 

Features of malignancy

- enlarging

- new or increasing pain

- perform biopsy

 

Technique

- excision difficult

- entering nerves usually sacrificed

- graft if needed

 

 

 

Malignant

Liposarcoma

Definition

 

STS composed of malignant lipoblasts

 

Epidemiology

 

Common 

- 10% of STS

- second only to MFH

 

Occurs almost exclusively in adults

 

Males age 40-60

 

Can be multiple origin -> examine patient

 

Rarely arise from lipoma

 

Differentiation

 

Many MFH's classified as liposarcoma in past

 

Liposarcoma S-100 +ve 

 

MFH negative to immunohistochemistry

 

Sites

 

Thigh / retroperitoneum / popliteal fossa / inguinal region

 

Almost always subfascial

- often between muscles or perivascular

 

Clinical

 

Painless mass or mild dull ache

 

No systemic complaints

 

Usually present late when tumour large

- especially retroperitoneal 

- no pain as tumour deep

 

Xray

 

Liposarcoma Xray

 

MRI

 

Deep to fascia / heterogenous

 

Liposarcoma Buttock MRILiposarcoma MRI 2

 

Liposarcoma

 

Metastasis

 

Pattern different to other STS

- 1/2 metastasise to lung

- 1/2 unusual non lung sites - retroperitoneum / mediastinum

 

Prognosis

 

Depends greatly on subtype & grade

 

Pathology

 

Gross

 

May quite large especially in retroperitoneal region

- well circumscribed & multilobulated

- soft, firm or rubbery

- colour based on mix of fat / myxoid / fibrous

- high grade = Necrosis

 

Histology

 

Diagnose by identifying typical lipoblasts 

- signet ring cells

- contains 1 or 2+ round cytoplasmic fat droplets which form sharp, scalloped indentatons on the nucleus

 

Liposarcoma vs Atypical Lipoma

 

Often difficult to differentiate low grade well differentiated liposarcoma from atypical lipoma

- if subfascial & non homogenous on MRI

- treat as STS 

- even if biopsy suggests benign

- high sampling error with biopsy

 

Classification

 

5 Types Histology

- treatment depends on grade & histology

 

1.  Well-Differentiated 30% 

- low grade 70% 5 year survival

- lipoma like

- risk of distant metastasis very low

- often recur after local excision

- death only with retroperitoneal metastasis

 

2.  Myxoid 50%

- low-grade 70% 5-year survival

- delicate plexiform capillary network

- translocation between 12 and 16

 

3 . Round Cell 10%

- high-grade 40% 5-year survival

- sheets poorly differentiated rounds cells

 

4.  Pleomorphic 20%

- high-grade 40% 5-year survival

- multivacuolated lipoblasts

 

5.  Dedifferentiated 

- due to heterogenity may be confused with other lesions

- myxoma / pleiomorphic lipoma/ myxoid chondrosarc / melanoma

- metastatic adenocarcinoma especially RCC

 

Management

 

Wide excision with radiotherapy

 

Results

 

Longhi et al J Clin Oncol 2008

- retrospective review

- compared preRT / postRT / chemo and no adjuvant treatment

- postop RT had best 5 year disease free survival at 82%

 

 

MFH

Definition

 

Malignant Fibrous Histiocytoma

 

Characterised by heterogenous population of pleomorphic spindle cells

- organised in a characteristic storiform or "starry night" pattern

 

Cell of origin unknown 

- primitive mesenchymal cell

- allowing both features of a macrophage (hence histiocyte)

- and collagen producing cell (hence fibroblast)

 

Epidemiology

 

Most common STS

- > 50 years old

- diagnosis largely replaced fibrosarcoma

 

Becoming less common again

- many being reclassified 

- basis of immunohistology 

- turning out to be poorly differentiated liposarcoma or malignant muscle tumours

 

NHx

 

Aggressive

- majority Grade II

 

Rare cases of multicentric tumours reported

 

Classification

 

Soft Tissue

 

Arise from primitive mesenchymal cells

 

Bone

 

A.  Primary 80%

- arise from bone mesenchymal cells

- exhibits both histiocytic & fibrous properties

 

B.  Secondary 20%

 

Occur in abnormal bone

- Paget's disease

- bone infarct 10%

- post DXRT

- multiple osteochondromatosis

 

Location

 

Most common in thigh

- 85% deep to fascia

- thigh > leg > arm > forearm

 

Retroperitoneal > 15cm

 

Bone 

- knee / femur / tibia / humerus

 

Clinical

 

"An aggressively enlarging, deep, and surprisingly mildly symptomatic soft tissue mass characterizes soft tissue MFH"

 

X-ray

 

Normal except for ST shadow

 

CT / MRI 

 

Large soft tissue mass

- arising from muscle

- patchy non-homogeneous areas

 

MFH Thigh Coronal MRIMFH Thigh MRI Axial

 

Bone

- metaphyseal purely lytic lesion

- ill-defined margins with cortical destruction

- no intra-tumour calcification

- may be seen arising from area of bone infarction 

 

Pathology

 

Gross

 

Solitary or multinodular

- margin usually discrete

- has fish-flesh appearance

- colour varies with proportion of stromal to cellular elements

- myxoid variant has white-grey, soft mucoid tumour lobules

- 5% undergo extensive necrosis & haemorrhage

 

Histology

 

Basic cellular constituents

1.  Fibroblasts in Storiform pattern

2.  Histiocyte like cells with vacuolated cytoplasm and evidence of phagocytosed hemosiderin, lipofuscin etc

3.  Mesenchymal cells

4.  Giant cells

5.  Inflammatory cell infiltrate not uncommon

 

Management

 

Principle 

 

Local control / wide resection if able

 

Radiotherapy if doubt about margins

 

Chemotherapy for metastasis

 

Prognosis

 

Best in I A/B 

- 50% 5 year survival

- 85% if < 5 cm

 

50% metastasis on diagnosis

 

50% recurrence rate

- local recurrence is aggressive

- causes significant morbidity

- doesn't alter overall survival

 

 

Other

Leimyosarcoma

Fibrosarcoma

Clear cell sarcoma

Epitheliod sarcoma

Neurosarcoma

 

Leimyosarcoma

 

Definition

 

Tumour of smooth muscle

- ? arises from vein wall

- very rare

- can arise from Leiomyoma

 

Clinical

 

Most common in elderly

 

Usually found in deep soft tissues

- especially retroperitoneum

- extremities

- GUT

- can see in uterine fibroids

 

Associated with NV bundle

 

Most common peripherally in

- groin

- popliteal fossa

 

Leimyosarcoma Femoral Vein MRI Coronal T2Leimyosarcoma Femoral Vein MRI Axial T2

 

Behaviour

 

Aggressive - early metastasis

 

Treatment

 

As for STS

- wide resection & DXRT

 

Fibrosarcoma

 

Definition

 

Malignant spindle cell neoplasm 

- produces a sparse to moderate amount of collagenous matrix 

- has no other matrix differentiation

 

Epidemiology

 

Since MFH, true Fibrosarcoma <10% STS

 

Primary tumour of mid-adults

- typically adult 20-60 yrs

 

M = F

 

Usually lower limb

 

Infantile & Congenital types exist

- better prognosis

- distal

 

DDx

 

FS v Fibromatosis

- the site, age, & histological findings must be carefully evaluated

- difficult to distinguish low grade fibrosarcoma from fibromatosis.

 

Fibrosarcoma

 

Pathology

 

Gross 

 

Arise from deep fascial or aponeurotic elements

- small tumour - well circumscribed

- larger - infiltrative

 

Histology

 

Principle cell the fibroblast

- spindle cell capable of producing collagen

- collagen easily identified in well differentiated specimens

 

Two varieties

 

1.  Well differentiated

- uniform spindle cells in fascicles

- herring bone pattern

 

2.  Poorly differentiated

- poor fascicular pattern

- increased pleomorphism

- many mitoses

- difficult to pick from MFH & both behave the same anyway

 

Immunohistochemistry

 

Masson's trichrome stain confirms the presence of collagen

 

Clear Cell Sarcoma

 

AKA Malignant Melanoma of the soft tissue

 

Characteristics

 

Small tumour 

 

Arises in conjuction with tendons & aponeuroses

- common around foot & ankle 50%

- young patients 20 - 40 years

 

Characteristic translocation

- t(12:22)

 

Clinical

 

Young male with tumour in foot and ankle

- think of clear cell sarcoma or synovial sarcoma

 

Metastasis

- lymphatic & haematogenous spread occurs

- enlarged local nodes require dissection

 

Pathology 

 

Gross

- solitary or multinodular firm mass 

- attached to tendons /aponeuroses

- rarely > 6cm 

- white to brown on its cut surface

 

Histology

 

Distinct fascicles & nests of spindle cells 

 

Uniform plump spindle cells 

- pale cytoplasm

- contain glycogen 

- melanin is present in 50%

 

Immunohistochemistry

 

Fontana preparation for Melanin

PAS for Intracellular Glycogen

 

Epithelioid Sarcoma

 

Characteristics

 

Odd small STT

- often misdiagnosed as benign ganglion

- ganglions occur in typical places

- if not, suspect more sinister diagnosis

 

50% arise forearm / wrist 

- number 1 Sarcoma of hand

 

Can arise in the dermis 

- can present with nodule or ulceration 

- simulates a cutaneous lesion eg granulomatous dermatitis

 

Tends to lymph node spread

 

Young adults compared with other STS

 

Pathology

 

Gross 

- arises in deep tissues especially near tendons, fascia 

- often firm & multinodular

- occasionally central necrosis 

 

Histology

 

Nodules or granuloma like collections of epithelioid cells

 

Epithelioid cells

- large cells

- deeply eosinophilic cytoplasm

- may transform to spindle cells

 

Characteristic feature is that of diffuse infiltration of tendon & fascial structures by elongated nests of tumour cells

 

Neurofibrosarcoma

 

Neurofibrosarcoma MRINeurofibrosarcoma Axial MRI Neurofibromatosis

 

AKA Malignant Schwannoma

 

Arise from peripheral nerves

 

Epidemiology

 

10% of STS

 

50% have NF

 

NF 

- 10% life risk & increases with age 

 

If not associated with NF then occur in older patients

 

Clinical

 

Painful mass

- previously painless, small stable tumour

- now painful

- enlarging

 

Often presents with neurological symptoms (arise on nerve)

- pain / paraesthesia / weakness

 

Pressure

- elicit pain & parasthesia in distribution of nerve

 

Site 

- Brachial plexus

- lumbosacral plexus

- major nerve trunks - especially the sciatic nerve

 

MRI

 

The MRI does not reliably distinguish a benign neurofibroma from one that has undergone transformation to a neurosarcoma

 

Pathology

 

Gross

 

Fusiform or bulbous swelling of a peripheral nerve

- usually deep

- infiltrates as it enlarges

- grey to white in cross section 

- areas of necrosis

 

Histology

 

Basic pattern of intersecting spindle cell fascicles

- herringbone

- very similar to fibrosarcoma & leiomyosarcoma

- wavy nuclei

- pallisading pattern ± whorled

- rare epithelioid variant

- similar melanoma or carcinoma

 

Prognosis

 

Most are high grade malignancies

- five year survival rate < 50%

- regional metastases to LN uncommon

 

Lung and bone are the commonest sites of distant metastases. 

 

Because of their association with the major neurovascular bundles, the vast majority of the lesions present in Stage II-B

Solitary neurosarcomas have a better prognosis than those associated with neurofibromatosis 1

Principles of ST Sacromas

Most common sarcomas Sarcoma Arm

 

1. MFH

2. Liposarcoma

3. Rhabdomyosarcoma (Paediatric)

4. Synovial Sarcoma 

5. Leiomyosarcoma

6. Fibrosarcoma

 

Ten Tissues of Origin

 

1.  Adipose / LS

2   Fibrous / FS

3.  Fibrohistiocytic / MFH

4.  Muscle / Leiomyosarcoma /  Rhabdosarcoma

5.  Vascular Tissue 

- haemangioendothelioma / angiosarcoma / kaposi's sarcoma

- malignant glomus / malignant haemangiopericytoma

6.  Synovial / Synovial Sarcoma

7.  Nerve / Malignant Schwannoma 

- neurofibrosarcoma

8.  Autonomic Ganglia / Neuroblastoma

9.  Bone / Cartilage - Extraskeletal OS & CS

10.  Uncertain

- alveolar soft part sarcoma / epitheliod sarcoma / extra-skeletal ewing's

- clear cell sarcoma / malignant melanoma of soft parts

 

2 most important prognostic factors

 

Size

Grade including metastases

 

DDx soft tissue mass

 

Malignant ST lesion

 

Benign ST lesion

- vascular (hemangioma, AVM, lymphangioma, glomus)

- neurogenic (NF, schwannoma)

- muscular (leiomyoma)

- fibroblastic (desmoid tumour, fibromatosis)

- fat (lipoma)

- simple cyst

 

PVNS / synovial chondromatosis

 

MO

 

FB

 

Malignancy - melanoma, metastatic

 

Clinical

 

Present as painless ST mass

- increasing in size

- becoming painful

 

Very rare to have systemic signs

 

Occurs 30 - 60 years

 

X-ray

 

DDx calcification

- hemangioma

- MO / HO

- synovial sarcoma / liposarcoma

 

MRI

 

Aim

- detects ST tumours

- determines anatomical extent 

- determines depth

- compartments / NV bundles

- characterises tumour

- plans resection / biopsy / approach

 

Staging

 

Locally

- MRI for soft tissue component

- MRA for vessel involvement

- +/- CT if intra-osseous

 

Systemic

- bone scan to detect intraosseous spread

- CXR and CT chest as per usual

 

Site

 

40% in lower limbs

50% in limbs

Remainder head neck and trunk

 

NHx

 

Act similar to sarcomas of bone

 

Exceptions

- usually remain intracompartmental

- significant incidence of lymphatic involvement in synovial and alveolar soft part sarcoma

 

Benign v Malignant

 

  Malignant Benign
Size > 5 cm < 5 cm
Location Deep to fascia Superficial to fascia
Feel Soft, mobile, nontender Firm, fixed, tender

 

Grade 

 

Depends on the usual histological findings

- mitoses, pleomorphism, necrosis, nuclear atypia

- can be difficult

 

Exception

- synovial sarcoma

- usually high grade

 

Staging

 

American Joint Committee on Staging of STS 1993

 

  Grade Size Spread
IA Low < 5cm  
IB Low > 5cm  
IIA Intermediate < 5cm  
IIB Intermediate > 5 cm  
IIIA High < 5 cm  
IIIB High > 5cm  
IVA Any   Lymph node
IVB Any   Metastasis

Modification 1997

 

Only low and high grades

Size

Depth

- important to prognosis

- i.e. subfascial

 

Prognosis

 

Now 5 year survival 50 - 80%

- combination wide resection and DXRT

 

Local recurrence doubles metastasis risk

 

Death from

- primary diseases / local recurrence

- lung / bone metastasis

 

Unfavourable 

- > 5 cm

- deep / extracompartmental

- inadequate excision

- histological high grade

 

Management

 

Principles

 

Wide Resection + DXRT 

- wide resection for local control

- DXRT to prevent local recurrence

- role of chemotherapy in adult STS uncertain

 

DXRT

 

Addition of DXRT has allowed limb salvage surgery without recurrence 

 

Irradiate all tissue at risk

- use filters & radiosensitisers

- local morbidity has decreased significantly in recent times

 

Pre-op DXRT

- 50 Gy in 2 Gy fractions

- higher doses than carcinoma

- shrinks tumour & makes resection easier

- increased complication rates

- surgery after 2-4 wks to allow skin to settle

 

Sarcoma Neck Pre and Post Radiation0002Sarcoma Neck Pre and Post Radiation0001

 

Post-op Brachytherapy ~ 10 Gy

 

Chemotherapy

 

No conclusive studies demonstrating efficacy of chemotherapy

 

Exception

- paediatric rhabdomyosarcoma

- high grade sarcomas

- treatment for lung mets (50% response rate)

 

Surveillance

 

For 10 years

- CXR every 3/12 for 2 years then 6/12 for 5 years

- physical examination of site for recurrence

- MRI site if concern

 

Recurrence

 

Local recurrence

- surgical excision & adjuvant DXRT

 

Lung Metastasis

- chemotherapy +/- surgical excision

- 20% survival at 5 years

 

Paediatric ST Sarcoma 

 

Different entity

- histololgically small cell

- different response to treatment

- good response to chemotherapy

- respond to surgical measures better as are fibrous based

 

Tumours

- rhabdomyosarcoma

- soft-tissue Ewing's

- PNET

- neuroblastoma

 

Rhabdomyosarcoma

Definition

 

Malignant tumour of striated muscle

 

Juvenile variety arises from mesenchyme

 

Thigh sarcomaSarcoma Thigh Axial

 

Epidemiology

 

Most common malignant ST Tumour in children (< 15 years)

- groin, head & neck

 

Recently, most adult rhabdomyosarcs reclassified as MFH

 

Types 

 

Four types "BEPA"

 

1.  Embryonal

 

Most common type 2/3

- arises in groin & head & neck > Urinary Tract & Retroperitoneum

- not common in extremities

- occurs in age < 10 years

- very aggressive

 

Histology

- poorly differentiated rhabdomyoblasts

- limited collagen matrix

- small blue round cell

 

DDx

- undifferentiated carcinoma / small cell OS / neuroblastoma / lymphoma / PNET / Ewing's

- IH desmin / myoglobin

- EM cross striations

 

2.  Alveolar

 

More common in extremities than trunk

- older 

- occurs in age 10-25 years

- ggressive

- histology similar to embryonal

- well differentiated round cells arranged in alveolar pattern separated by thick fibrous septa

 

3.  Botryoid 

 

"Bunch of Grapes"

- uncommon

- ccurs in hollow viscus

- particularly the bladder

- grape like clusters of round cells beneath the mucosal lining of hollow organs

- EM studies: sarcomere formation and cross striations

 

4.  Pleomorphic

 

Rare

- occurs in adults

- deep portions of the extremities

- arises skeletal muscle

- dark red lobulated mass

 

Histology

- spindle shaped cells with marked variation in size / shape

- bizarre gigantic cells 

- cells can resemble a wrist watch

 

DDx

- MFH

- EM / IHC

 

Genetics

 

Characteristic translocation

- t(2:13)

 

Management

 

Principles

 

Neoadjuvant Chemotherapy

- exception to usual management for STS

 

Wide surgical resection 

- total excision of involved muscle

 

DXRT

- if resection not possible or incomplete

 

Prognosis

 

Depends on resection & stage

- complete resection, 85% 5 year survival

- macroscopic residual disease or distant metastases, 50% 5 year survival

 

 

Synovial Sarcoma

Epidemiology

 

4th most common STS

- 10-35% of STS

 

Peak age 3rd-4th decade

- rare in children

 

Pathology

 

Cellular characteristics suggest tumour arises from primitive synovial cells

- rarely actually occurs within joint

 

Characteristic

 

Occasionally metastasis to lymph nodes (5-7%) 

- like Epitheloid Sarcoma 

- feel nodes in examinaiton

 

Classically show mineralization

- see on knee X-ray

 

Most common STS of foot

 

Synovial Sarcoma Foot MRI0001Synovial Sarcoma Foot MRI0002

 

Rarely intra-articular

 

Location

 

Deep soft tissues

- often centered on tendons, bursa and joints

- head, neck & trunk 15%

- extremities 50% / knee

- hands & feet 10% / often mistaken for ganglion

 

X-ray

 

May have calcification or ossification in tumour

 

DDx Soft Tissue Lump with calcification

 

Malignant ST tumour

 

Benign ST tumour - hemangioma / AVM

 

Malignant bone tumour - OS

 

Myositis Ossification

 

DDx lymph node metastasis

 

Clear cell sarcoma

Rhabdomyosarcoma

TB! - Calcified lymph node

 

MRI

 

Knee

- heterogenous mass, not communicating with joint

 

DDx Baker's cyst

- semimembranosus

- communicates with joint

- between semimebranosus tendon and medial head gastrocnemius

 

Bakers Cyst MRIBakers Cyst MRI

 

Histology

 

Difficult to grade 

- all considered high grade

- more extensive calcification suggests better prognosis

 

A. Biphasic Type

- classic pattern

- contains 2 distinct cell types

- epitheliod cells which resemble adenocarcinoma

- form gland like structures lined by cuboidal cells

- malignant spindle cells

 

B. Monophasic Type

- as common as classic biphasic

- spindle cells only 

- difficult to DDx from fibrosarcoma

 

Cytogenetics

 

Have a characteristic translocation

- t(X:18)

 

Management

 

Pre-op DXRT & Resection

 

Limb salvage may be possible

- amputation preferred in hand & foot

 

Post operative chemotherapy

 

Prognosis

 

70% 5 year survival rate

 

Metastases occur in 50%

 

Poor prognosis 

- local recurrence 

- inadequate resection 

- large size / monophasic / mets

 

Better prognosis

- heavily calcified

- <5cm