Introduction

• Standard technique to support diagnosis of inflammatory, proliferative, reactive and neoplastic conditions within tissue.
• Biopsy refers to the collection of a sample of intact tissue for examination of tissue microarchitecture and structural change. This is distinct from cytopathology which is based on assessment of individual cells or groups of cells derived from a tissue lesion.

Uses

• Confirmation of diagnosis or rule-outs.
• Biopsies are taken to:
  • Establish a specific diagnosis.
  • Eliminate other clinical diagnoses.
  • Follow the course of the disease.
  • Confirm the completeness of excision of a tumor by evaluation of tumor margins. Additionally, biopsy evalutes the potential for metastatic spread of a neoplasm by evaluating vascular or lymphatic invasion.
• Biopsy specimens are used for several clinical purposes including:
  • Histological diagnosis involving examination of hematoxylin and eosin-stained sections of tissue by light microscopy. 
  • Special tests:
    • Application of histochemical stains to tissue - for example to detect organisms (eg Gram stain Staining techniques: Gram stain, periodic acid Schiff stain Staining techniques: Periodic acid/schiff, Grocott stain or ZN stain Staining techniques: Ziehl-Neelson) or evaluate the presence of collagen, fibrin, amyloid etc.
    • Immunohistochemistry/immunofluorescence  Immunohistochemistry (IHC) - for example to specifically identify micro-organisms, to phenotype neoplastic cells, determine the nature of extracellular matrix tissue or identify deposits of immunoglobulin or complement within tissue lesions.
    • Fresh biopsy tissue may be submitted directly for microbial culture.
    • Molecular diagnostics for example the use of polymerase chain reaction (PCR PCR (Polymerase chain reaction)) for detection of infectious agent, or clonality testing to determine whether a lymphoid infiltration is reactive or neoplastic.
  • Types of biopsy include:
    • Bone marrow needle core biopsy Bone marrow aspiration.
    • Excisional biopsy of tissue such as lymph node.
    • Incisional biopsy of viscera or mass lesions within viscera or skin Biopsy: skin.
    • Punch biopsy of skin.
    • Needle core biopsy of lymph node, liver Biopsy: hepatic, or kidney Biopsy: kidney.
    • Ultrasound-guided needle biopsy of internal viscera Biopsy: ultrasound-guided  Fine needle aspirate: ultrasound-guided.
    • Endoscopic biopsy of respiratory or gastrointestinal mucosa Flexible endoscopy Gastroscopy Enteroscopy.
    • Biopsy samples may be either fixed in neutral buffered formalin (generally) or fresh frozen for cryosectioning.

Advantages

• Can be the most effective way to establish a definitive diagnosis.
• Facilitates assessment of prognosis and treatment.
• Excisional biopsy may result in cure if the biopsy procedure removes the lesion.

Disadvantages

• Invasive in some cases and requires local or general anesthesia General anesthesia: overview.
• Correct tissue is not always accessible without complex procedures.
• Minor interference has been suggested to possibly exacerbate some neoplastic and reactive conditions although the evidence for this actually occurring is limited.
• Biopsy is a relatively slow diagnostic procedure - tissue samples require processing, so turn-around time is generally 24 hours.

Requirements

Preparation

Procedure

Aftercare

Outcomes

Prognosis

• Good in all cases if planned properly.

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.