Soft Tissue Tumor Biopsy

KEY FACTS

Terminology

• Percutaneous biopsy of soft tissue tumor under US guidance

Accurate, safer, and more cost-effective alternative to open biopsy for tissue diagnosis

Preprocedure

• To determine nature and make specific diagnosis of indeterminate soft tissue mass

Biopsy not required in cases in which reliable specific diagnosis made by imaging alone
• High-frequency (7-12 MHz) linear array transducer
• Coaxial system preferred

15-g coaxial needle with 16-g Tru-Cut needle

Procedure

• US area of interest to best assess route and select viable areas of lesion before biopsy

Target solid area, preferably with evidence of neovascularization on color Doppler

Avoid cystic or necrotic areas

Obtain 1 biopsy close to edge of tumor
• Avoid important intervening structures, such as uninvolved compartment, neurovascular bundle, tendon, bowel, or other organs, especially in case of pelvic biopsy
• Keep needle path within area of planned surgical resection

Post Procedure

• Local complication is very uncommon

Outcomes

• Occasionally, tissue obtained may not be representative of entire tumor
• Theoretical risk of tumor seeding along biopsy pathway

Risk much smaller than with open biopsy

TERMINOLOGY

Abbreviations

• Fine-needle aspiration for cytology (FNAC)

Definitions

• Percutaneous biopsy of soft tissue tumor under US guidance

PREPROCEDURE

Indications

• Establish specific histologic diagnosis of soft tissue mass lesion with indeterminate imaging findings
• Confirmation and tumor typing of suspected soft tissue sarcoma
• Confirm or exclude musculoskeletal metastases in patient with known primary tumor
• Confirm or exclude tumor recurrence in patient with prior tumor resection
• Provide tissue for histologic and microbiologic analysis in patient with suspected soft tissue infection
• Provide tissue for histologic analysis in patient with suspected inflammatory myositis

Contraindications

• Uncorrected bleeding diathesis
• Uncooperative patient
• Site inaccessible to US access
• Soft tissue mass too small for percutaneous biopsy

Lesions < 1 cm in diameter are generally not amenable to percutaneous biopsy; FNAC more appropriate
• High-flow vascular anomaly or tumor in site inaccessible to postbiopsy tamponade

Most highly vascularized tumors can be safely biopsied provided they are located in area where adequate percutaneous tamponade can be applied post biopsy

Getting Started

• Things to check

Patient identity, type of procedure, side of procedure, informed consent

If patient taking anticoagulants, optimize clotting profile before procedure

– Optimal level depends on perceived difficulty in applying adequate percutaneous tamponade post biopsy

Review prior imaging

– Accurate specific imaging diagnosis may be made in large number of soft tissue masses, e.g., lipoma, epidermoid cyst, vascular malformation, and nerve sheath tumor

Percutaneous biopsy is unnecessary if diagnosis is certain on imaging

Biopsy is unnecessary intervention, potentially hazardous, and can be painful (e.g., if nerve sheath tumor is biopsied)

– In other situations, e.g., distinguishing well-differentiated liposarcoma from lipoma, requires histologic examination of whole tumor mass

– Plan suitable needle path and decide on area to be sampled, particularly targeting viable tumor area and avoiding neurovascular bundle
• Medications

Local anesthetic (2-3 mL 1% lignocaine) to skin

Sedation of anxious patient or young children

– Intravenous midazolam or other benzodiazepine; antidote and resuscitation facilities should be available
• Equipment list

High-frequency (7-12 MHz) linear-array transducers should be used routinely

Sterile biopsy set

Biopsy needle type: Spring-loaded cutting needles are most commonly used

– Tru-Cut needles employ inner troughed needle, which is advanced into lesion, with outer cylindrical cuff isolating core of tissue

– End-cutting needles, e.g., Franseen, obtain tissue by isolating core within end of advancing needle cylinder

Biopsy needle size

– Large core (14- to 18-g) biopsy needle

Larger biopsy needle provides more tissue for histology, ensuring sufficient tissue is available for immunohistochemical staining and molecular studies

As risk of bleeding from easily compressible lesions is low, there is no advantage to using smaller needles for most musculoskeletal biopsies

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Tags: Diagnostic Ultrasound Musculoskeletal

Apr 9, 2020 | Posted by admin in MUSCULOSKELETAL IMAGING | Comments Off

KEY FACTS

Terminology

TERMINOLOGY

Abbreviations

PREPROCEDURE

Indications

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Soft Tissue Tumor Biopsy

Soft Tissue Tumor Biopsy

Preprocedure

Procedure

Post Procedure

Outcomes

Definitions

Contraindications

Getting Started

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Soft Tissue Tumor Biopsy

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