Bone Tumor Biopsy Principles

Biopsy of a suspected bone tumour is one of the most consequential procedures in musculoskeletal oncology. An incorrectly placed or technically inadequate biopsy can contaminate tissue planes, compromise limb salvage, lead to unnecessary amputation, or result in diagnostic failure. Every trainee and consultant orthopaedic surgeon must understand the principles governing biopsy planning, technique, and tissue handling for bone tumours.

• Mankin principle (1982): wrong biopsy placement was the single most common cause of preventable amputation in bone sarcoma patients — this landmark study established that biopsy of bone tumours must be performed at or coordinated with the treating sarcoma centre
• The biopsy tract becomes contaminated with tumour cells — it must be excised en bloc with the tumour specimen at definitive surgery
• A poorly planned biopsy that contaminates adjacent compartments, neurovascular bundles, or joints may render a potentially limb-salvageable tumour unresectable without amputation
• All staging imaging (MRI of the entire bone, CT chest, bone scan) must be completed BEFORE biopsy — biopsy changes tissue planes and MRI signal, making subsequent staging unreliable
• Biopsy should be performed by, or in direct communication with, the surgeon who will perform the definitive resection — this ensures the tract is placed in the correct location for subsequent en bloc excision

• Plain radiographs (AP and lateral): characterise lesion matrix, periosteal reaction, zone of transition, host bone response
• MRI of the entire affected bone (pre-biopsy): defines intramedullary extent, soft tissue involvement, skip lesions, neurovascular proximity, and articular involvement; guides biopsy approach and definitive surgery planning; MRI must be done BEFORE biopsy — post-biopsy haematoma obscures tumour margins
• CT scan: characterises matrix (mineralisation, calcification), cortical integrity, and lesion compartment; essential for CT-guided needle biopsy planning
• CT chest: pulmonary metastasis assessment; baseline before any treatment
• Bone scan: whole-body skeletal survey for polyostotic disease and skip lesions
• Bloods: FBC, ESR, CRP, LDH, ALP, serum protein electrophoresis (SPEP), PSA (in appropriate age groups) — exclude infection and metastatic carcinoma mimicking primary bone tumour
• PET-CT: increasingly used for staging and identification of most metabolically active biopsy target in heterogeneous tumours

• Core needle biopsy is the gold standard first-line technique for bone tumour biopsy — diagnostic accuracy 90–95%; minimal contamination; preserves options for definitive surgery
• Open biopsy reserved for: failed needle biopsy (non-diagnostic after two attempts), lesions requiring architectural diagnosis (e.g., low-grade central osteosarcoma vs fibrous dysplasia), or when frozen section is needed to guide extent of resection
• Excisional biopsy is categorically contraindicated for any lesion suspected to be malignant — if the lesion proves to be a sarcoma, contaminated margins make curative resection impossible or require extensive reconstruction

• Longitudinal incision: always longitudinal (in line with the limb) — NEVER transverse; a transverse incision contaminates a wide swath of skin and subcutaneous tissue that cannot be excised without skin graft or flap at definitive surgery
• Minimum tissue planes contaminated: direct approach through one muscle to tumour without traversing intermuscular planes; avoid entering adjacent compartments
• Strict haemostasis: meticulous haemostasis throughout; haematoma dissects along tissue planes and contaminates them with tumour cells; use bipolar diathermy; compress the biopsy site after sampling
• Drain placement: if a drain is used, it must exit directly through the wound (in line with the incision) — NEVER through a separate stab incision, as the drain track will be contaminated and must be excised at definitive surgery; a separate drain exit requires separate excision
• Cortical window: use the smallest cortical window necessary; oval or circular window preferred over square (stress riser risk reduced); place in line with the planned resection; supplement with PMMA plug or bone wax after sampling
• Send for microbiology as well as histology — infection can mimic bone tumour both clinically and radiologically; dual processing prevents missed diagnosis
• Tourniquet use: tourniquet may be used to improve visibility but must be deflated and haemostasis achieved before wound closure — residual bleeding spreads contamination; exsanguination by Esmarch bandage is contraindicated (squeezes tumour cells distally)

• Fresh tissue (not in formalin): a portion should always be sent fresh — allows molecular studies (FISH, PCR, next-generation sequencing), cytogenetics, flow cytometry, and microbiological culture; formalin fixation destroys RNA and some molecular targets
• Formalin-fixed paraffin-embedded (FFPE): standard histology processing; enables H&E morphology, immunohistochemistry (IHC), and some molecular testing from paraffin-embedded material
• Frozen section (intraoperative): used to confirm adequacy of sample before closing — not for definitive diagnosis; confirms representative tissue obtained
• Always inform the pathologist of the clinical and radiological differential diagnosis — bone tumour pathology is highly context-dependent; the same histological appearance can mean different things in different age groups, locations, and radiological contexts
• Non-diagnostic biopsy: do not proceed to resection on the basis of a non-diagnostic biopsy — repeat the biopsy targeting a different site; consider PET-CT to identify the most metabolically active area for re-biopsy
• Necrotic tissue: chemotherapy or embolisation may cause necrosis before biopsy; target viable peripheral areas; avoid necrotic core

• Mankin study (1982) and its replication (2000): showed that biopsy-related complications were significantly higher at referring institutions vs treating sarcoma centres — 10× higher rate of unnecessary amputation, 3× higher rate of non-representative tissue; central principle: refer for biopsy, do not attempt at district general hospital without specialist guidance
• Frozen section limitations: frozen section can confirm tissue is representative (viable tumour vs necrosis vs normal bone) but cannot reliably grade sarcomas or diagnose most bone tumours definitively — do not change surgical plan based on frozen section alone unless it changes the fundamental approach (e.g., confirming metastatic carcinoma in an elderly patient)
• Molecular testing panel: modern bone sarcoma diagnosis increasingly relies on molecular markers — EWSR1 rearrangement (Ewing sarcoma), MDM2 amplification (parosteal osteosarcoma/low-grade central osteosarcoma), USP6 rearrangement (ABC), H3F3A mutation (GCT), SS18-SSX (synovial sarcoma), FUS-DDIT3 (myxoid liposarcoma); fresh tissue is essential for these assays
• Biopsy in the context of pathological fracture: haematoma from fracture contaminates adjacent compartments; the contaminated haematoma must be considered part of the tumour zone at definitive surgery; wide resection margins must account for the fracture haematoma extent; MRI of the entire haematoma field is essential
• When to suspect metastatic disease rather than primary bone tumour: age >40, polyostotic lesions, vertebral body involvement, destructive lytic lesion without periosteal reaction in an elderly patient — screen with SPEP, PSA, CT chest/abdomen/pelvis, and bone scan before performing biopsy to direct the most informative sampling strategy

• Mankin principle: wrong biopsy = preventable amputation; refer to treating sarcoma centre; do not biopsy at DGH without specialist involvement
• MRI BEFORE biopsy — post-biopsy haematoma obscures tumour margins and staging is unreliable
• Core needle biopsy: gold standard; 90–95% diagnostic accuracy; minimal contamination; preferred over open biopsy
• Open biopsy rules: longitudinal incision; one compartment only; strict haemostasis; drain in line with incision; smallest cortical window; microbiology AND histology
• Excisional biopsy: NEVER for potentially malignant lesions — if sarcoma found, margins contaminated and curative surgery compromised
• Transverse incision: NEVER — contaminates wide skin/soft tissue swath; cannot be excised without major reconstruction
• Distal femur biopsy: anteromedial/anterolateral — NEVER posterior (popliteal fossa contamination = amputation)
• Fresh tissue: always send a portion fresh for molecular studies; formalin destroys RNA and molecular targets
• Drain exit: must be in line with the wound — not through separate stab; drain tract is contaminated and must be excised
• Non-diagnostic biopsy: repeat; target viable peripheral tissue; use PET-CT to identify most active area