Biopsy Principles - Pathology

Introduction
Purpose of the biopsy is to confirm a suspected diagnosis The biopsy is not a substitute for a thorough history, physical exam, and laboratory investigation prerequisites for a biopsy CBC, platelets, coagulation studies cross-sectional imaging to evaluate local anatomy treatment center performing biopsy must be capable of proper diagnosis and treatment

Indications for Biopsy

Indications
- aggressive bone or soft tissue lesions
- soft tissue lesions larger than 5cm, deep to fascia, or overlying bone/neurovascular structures
- unclear diagnosis in a symptomatic patient
- solitary bone lesions in a patient with history of carcinoma
When a biopsy is not indicated
- asymptomatic latent bone lesions or a symptomatic active bone lesions which appear entirely benign on imaging don't necessarily need a biopsy
- soft tissue lesion which are completely benign on MRI don't necessarily need a biopsy (e.g. lipoma, hemangioma)

Types of Biopsy

Fine Needle Aspiration (FNA)
- provides cytologic (cellular) specimen
- frequently used for carcinoma
- not typically used for sarcoma
Core biopsy (Tru-cut)
- allow for tumor structural examination
  - can evaluate both the cytologic and stromal elements of the tumor
- frequently used for sarcoma
Incisional biopsy
- small surgical incision carefully placed to access tumor without contamination of critical structures
Excisional biopsy
- select indications: small, superficial soft tissue masses

Principles of the Open Incisional Biopsy

Incision
- use longitudinal incision in the extremities
  - allows for extension of the incision for definitive management
Approach
- do not expose neurovascular structures
  - all tissue exposed during the biopsy is considered contaminated with tumor
- maintain meticulous hemostasis
  - post-operative hematomas are considered contaminated with tumor
  - release tourniquet prior to wound closure
Biopsy
- perform through the involved compartment of the tumor
- for bone lesions with a soft tissue mass, it is ok to perform the biopsy using the soft tissue mass
Closure
- if using a drain, bring drain out of the skin in line with surgical incision
  - allows drain site to be removed with definitive surgical extensile incision