Michelle Ghert, MD, FRCSC

300/100,000 benign soft-tissue, but only 2/100,000 malignant soft-

tissue Soft tissue sarcoma can occur at any

age Rabdomyosarcoma most common in children

Synovial & epitheliod sarcomas common in young adults

20-40% of STS occur in extremities 1/3 in upper extremities & 2/3 lower

extremities 30% occur in trunk and pelvis. 10% occur in head & neck 1/3 of STS present as small superficial

masses

Fibrous Tissue Adipose Tissue Striated Tissue Smooth Tissue Synovial Tissue Blood Vessels Lymph Vessels Peripheral Nerve Myofibroblast

Fibroma/Fibrosarcoma Lipoma/Liposarcoma Rhabdomyoma/Sarco Leiomyoma/Sarcoma Mesothelioma Angioma/Sarcoma Lymphangioma/sarco Neuroma/

Schwannoma Malignant Fibrous

Histiocytoma

Superficial tender mass, red in color,rapidly enlarging, swollen, warm, fluctuant on examination?

1)Synovial cyst2)Hematoma3)Abscess

Hx of direct trauma, therapeutic anticoagulation, clotting deficiency, subcutaneous ecchymosis, compressible on examination?

1)Abscess2)Hematoma3)Synovial Cyst

Para-articular mass, trans-illuminate, fluctuation in size independent of activities, tense but indentable with digit pressure on examination?

1) Bakers cyst2) Hematoma3) Shwannoma4) Synovial Cyst

Malignant:Pleiomorphic SarcomaFibrosarcoma(FS)LiposarcomaSynovial SarcomaEpitheliod SarcomaClear Cell SarcomaRhabdomyosarcoma

Benign:1-Lipoma2-Desmoid3-Schwannoma4-Hemangioma

Size: < 5cm

Depth: Superficial

Grade: Low

>= 5cm

Deep

High

LOW GRADE: HIGH GRADE:

Good Differentiation Hypocellular More Stroma Hypovascular Minimal Necrosis

Poor Differentiation Hypercellular Minimal Stroma Hypervascular Much Necrosis

Very little information is gained. Some infections may result in elevated: WBC, ESR & CRP But this finding nonspecific. Elevated lactate dehydrogenase seen

in lymphoma. Suspicion of Gout----- Serum Uric Acid

Confirm the diagnosis of a cyst Does mass have a cystic component? F/U a small mass that is being followed

without excision Accurately asses an increase in growth

of the mass by examining the change on the ultrasound studies

Identifying and characterizing mineralization within the soft tissue masses(myositis ossification)

Generally reserved for staging

Most sensitive and specific radiograph study for imaging soft tissue masses

Helpful for preoperative planning prior to excision the mass

Excellent differentiation of various tissue types

Indication:

1- Clinical & radiographic evaluation does not yield a conclusive diagnosis

2-When the mass must be removed

2 CRITERIA SHOULD BE MET BEFORE 2 CRITERIA SHOULD BE MET BEFORE PROCEEDING:PROCEEDING:

1) The pathologist should have experience in musculoskeletal pathology

2)The surgeon should have experience in dealing with all of the possible diagnoses considered in the pre-biopsy differential diagnosis

Fine-needle aspiration

Core-needle

Open biopsy

Typically performed by an interventional or MSK radiologist

Minimal morbidity for the patient Core is better than FNA Core is 85% diagnostic If non-diagnostic tissue is

obtained, the mass should not be assumed to be benign

Incision in line with resection incision Longitudinal in extremities Intramuscular if possible (to bury

hematoma) Avoid NV structures and joints No skin or muscle flaps Meticulous hemostasis Tight closure Approach soft tissue mass or weakened

area of bone Drain if necessary, in line and distal to

incision Send tissue for frozen: ‘lesional tissue’

Treatment of soft tissue masses is based on their size and location

4 categories: small superficial large superficial small deep large deep

The piecemeal removal of the tumor. Benign proliferative lesions (PVNS,

gout)

Complete removal of the tumor with pseudocapsule left intact

Benign tumors

Removal of the tumor with a cuff of normal tissue without exposing the pseudocapsule

Malignant soft-tissue lesions

Involves removal of the entire muscle compartment or compartments involved by the tumor

Rare

Less than 5cm Easily palpable beneath the skin & not

firm with muscle contracture Slow or stable growth pattern Long history

If excisional biopsy is chosen, then marginal excision can be done

Deep fascia should be left undisrupted

More than 5 cm. Easily felt beneath the skin, and not

firm with muscle contracture.

Almost always need evaluation with MRI

If a diagnosis is unclear by MRI, then biopsy

Less than 5 cm located in deep fascia Becomes more firm with muscle

contracture Small deep mass should be always

investigated by MRI

If MRI suggests a lipoma or peripheral nerve sheath mass (shwannoma), marginal excision

Non-specific MRI may represent a soft tissue sarcoma

More than 5cm located deep to the fascia.

MRI (high risk) Refer to musculoskeletal oncologist

Wide surgical excision Radiation, pre or post operative Chemotherapy, while controversial, can

be considered for patient with high grade, large, deep soft tissue sarcoma

Longstanding, small, static subcutaneous ‘bumps’ can be treated with ultrasound, observation and marginal excision if desired

Rapid growth, deeper lesions and those 4-5 cm should be imaged with MRI

High-risk lesions should not be excised, but biopsied

Always use longitudinal incision in extremities