Types of Biopsy

1. Needle Biopsy

a) Fine Needle Aspiration (FNA / FNAC)

• A 20-22G needle is used to aspirate cells
• Provides cytological information only - no tissue architecture
• Cannot distinguish invasive from non-invasive tumour (e.g., invasive vs. in-situ breast carcinoma)
• Relatively safe, quick, and performed under palpation or image guidance
• Best for: thyroid nodules, lymph nodes, salivary gland masses, solid breast masses

b) Core Needle Biopsy (CNB / Trucut Biopsy)

• 14-16G cutting needle (e.g., Travenol Tru-cut, Vim-Silvermann needle) removes a core of tissue
• Provides histological information - tissue architecture is preserved
• More advantageous than FNA when histologic findings affect therapy (e.g., distinguishing atypical ductal hyperplasia from carcinoma)
• Can be done by direct palpation or with CT/ultrasound/stereotactic imaging guidance
• Risk: 19-44% false-negative rate for atypical ductal hyperplasia on core biopsy

"Core biopsy specimens, like fine-needle aspirations, have the disadvantage of introducing sampling error." - Schwartz's Principles of Surgery, 11th ed.

c) Drill Biopsy

• A small sharp cannula attached to a high-speed compressed-air drill
• Primarily used for breast lumps
• Accuracy >90% claimed for breast pathology
• Considered superior to simple needle biopsy for this indication

2. Punch Biopsy

• A circular cutting instrument (punch, 2-8 mm diameter) is rotated through the skin/mucosa under pressure
• Skin is stretched perpendicular to relaxed skin tension lines before punching - this creates an elliptical wound that can be sutured linearly
• Reaches epidermis, papillary dermis, and reticular dermis; deeper than shave biopsy
• Requires sutures
• Used for: dermal lesions, inflammatory skin diseases, infectious processes, subcutaneous lesions
• Also used endoscopically (punch forceps) for mucosal lesions of GI tract, bladder, bronchus
• A variation allows "narrow-hole extrusion" to remove larger benign subcutaneous growths (e.g., lipoma) through a small cutaneous portal

• Andrews' Diseases of the Skin, p. 1020

3. Shave Biopsy

• A No. 15 blade scalpel or flexed razor blade makes a horizontal incision through elevated skin lesions
• Lesion is pinched between fingers and removed with sweeping strokes
• Specimen: epidermis + papillary dermis (occasionally reticular dermis in elevated lesions)
• Heals by second intention; no sutures needed
• Best for: pedunculated/papular/exophytic lesions, superficial BCCs, SCC in-situ, lentigo maligna, benign nevi for recontouring
• Disadvantage: inadequate for deep dermal or subcutaneous pathology (e.g., discoid lupus erythematosus)

Saucerization (Deep Shave) Biopsy

• A shave variant where the blade is angulated to go deliberately deeper
• Provides the entire lesion or a large portion for histological analysis
• Preferred for: atypical melanocytic nevi where thin melanoma is in the differential, hypertrophic AK vs. minimally invasive SCC, keratoacanthoma

4. Open (Surgical) Biopsy

a) Incisional Biopsy

• Only a wedge or slice of tissue is removed from part of the lesion (typically from the thickest/darkest margin), along with some adjacent normal tissue
• Indicated for large lesions where excisional biopsy is not feasible (e.g., face, hands, feet, or anatomically constrained locations)
• Theoretical disadvantage: may spread tumour cells to adjacent tissues
• Always sample the margin of a lesion, not the necrotic centre

b) Excisional Biopsy

• The entire lesion is excised with a margin of healthy surrounding tissue
• Preferred and safer approach where feasible
• Allows full histopathological examination of the entire specimen
• Detects malignant change within a presumed benign tumour
• Curative intent: surgeon must ensure negative margins, orient the specimen with sutures/clips, and ensure the incision directly overlies the area (no tunnelling)
• Indicated for: pigmented lesions suspicious for melanoma, lesions where core biopsy is non-diagnostic

"Whenever possible, excisional biopsy should be carried out in case of suspected tumours." - S Das, Manual of Clinical Surgery, 13th ed.

5. Scissors (Snip) Biopsy

• Iris or Gradle scissors snip the base of a pedunculated lesion
• Often no anaesthesia required
• Tissue above the epidermal connection is removed
• Heals by second intention
• Best for: skin tags, fibroepithelial polyps

6. Curettage Biopsy

• A curette scrapes lesions involving the epidermis (e.g., seborrhoeic keratoses, actinic keratoses, verrucae)
• Provides epidermal sheets or fragments of epidermis and dermis
• Also used to confirm BCC clinically prior to definitive treatment
• No sutures; heals by second intention

7. Endoscopic Biopsy

• Biopsy forceps passed through the working channel of an endoscope (colonoscope, bronchoscope, cystoscope, gastroscope)
• Forceps are opened, pressed into the lesion, closed, and withdrawn
• Key principles:
  • Biopsy from the margin/edge of an ulcer or suspicious area, not the necrotic base
  • For gastric ulcers: four-quadrant biopsy from the edges
  • Polyps should be completely excised rather than partially biopsied (muscularis mucosae invasion can't be assessed from a fragment)
  • Barium enema should not be performed within 10 days of a GI biopsy (risk of perforation)
  • Contraindicated in patients on anticoagulants

8. Sentinel Lymph Node Biopsy (SLNB)

• A minimally invasive technique to sample the first draining lymph node(s) from a primary tumour
• Lymphatic mapping uses blue dye (e.g., patent blue) ± radiolabelled colloid injected peritumorally
• Avoids full lymph node dissection (and its morbidity) in patients whose sentinel node is negative
• Standard staging for melanoma and breast cancer
• Must be performed prior to wide local excision of the primary

Summary Table

• S Das, A Manual on Clinical Surgery, 13th ed.
• Schwartz's Principles of Surgery, 11th ed.
• Andrews' Diseases of the Skin, Clinical Dermatology
• Dermatology, 5th ed. (Elsevier)
• Fitzpatrick's Dermatology, 9th ed.
• Pfenninger and Fowler's Procedures for Primary Care, 3rd ed.

Classification of Biopsy in Dentistry (Oral and Maxillofacial Surgery)

I. Based on Access / Location of the Lesion

II. Based on Technique (Primary Classification)

1. Incisional Biopsy

• Removes only a representative portion of the lesion plus a margin of adjacent normal tissue
• Preferred when the lesion is >1 cm in diameter, shows differing characteristics at different sites, or is suspected malignant/premalignant
• Key surgical principles:
  • A wedge-shaped incision is made, wide at the surface and converging at depth
  • Biopsy from the active periphery (margin), not the necrotic/ulcerated centre
  • A narrow, deep specimen is better than a broad, shallow one
  • Include adequate depth to capture the base of the lesion
  • In a large lesion with differing zones, multiple samples are taken and each placed in a separately labelled container, with a schematic diagram submitted to the pathologist
• Indications:
  • Large lesions not amenable to complete excision
  • Suspected carcinoma or precancerous lesion (leukoplakia, erythroplakia)
  • Lesion with diffuse or irregular borders
  • Pigmented, vascular, or indurated lesions
  • Deeply infiltrating lesions

2. Excisional Biopsy

• The entire lesion is removed with a 2-3 mm perimeter of normal tissue all around
• Indicated for lesions ≤1 cm that are clinically benign
• If the lesion appears malignant, pigmented, vascular, or has diffuse borders, an additional 2-3 mm of normal-appearing peripheral tissue is taken
• Often constitutes definitive treatment as well as diagnosis
• Lesion depth must be assessed by palpation before incision; the incision should exceed the total depth of the lesion slightly
• Incisions should be oriented parallel to nerves, blood vessels, and lines of muscular tension (smile lines, facial creases) to minimize secondary injury and improve aesthetics
• Indications: small benign-appearing lesions (fibroma, mucocele, small papilloma, retention cysts)

"Complete excision often constitutes definitive treatment of the lesion biopsied." - Biopsy in Oral and Maxillofacial Surgery, University of Mosul lecture series, 2025

3. Aspiration Biopsy

a) Diagnostic Aspiration (Fluid Aspiration)

• Used to determine if an intraosseous radiolucent lesion contains fluid, blood, or air before entering a bony cavity
• Rules out vascular lesions (aspiration of blood = avoid entering lesion)
• Distinguishes cystic from solid lesions
• A 16-18 gauge needle connected to an aspirating syringe is used
• Aspiration is performed on any fluid-filled lesion except a mucocele
• Must always be done before incising into jaw cysts or radiolucent bone lesions

b) Fine Needle Aspiration Biopsy (FNAB)

• A finer needle aspirates cells for cytopathological diagnosis
• Used when:
  • A soft tissue mass is detected beneath the skin/mucosa and the patient wishes to avoid a scar
  • Adjacent anatomy makes open biopsy risky (e.g., proximity to facial nerve)
  • Diagnosis of neck masses and parotid gland lesions (FNAB is increasingly preferred for parotid due to its non-invasive nature)
• Provides cytology only - no tissue architecture; cannot distinguish invasive from in-situ tumour

4. Cytologic Biopsy (Exfoliative Cytology / Brush Biopsy)

• Cells are obtained from the surface of an oral lesion by scraping/brushing without formal surgical incision
• Exfoliative cytology: gentle scraping with a spatula; provides surface epithelial cells only
• Brush biopsy (OralCDx): a brush is rotated firmly on the lesion to obtain transepithelial cells from all layers of the epithelium
• The smear is fixed, stained, and examined microscopically
• Advantages: quick, non-invasive, no anaesthesia, no wound
• Limitations: false negatives occur; a positive result still requires confirmatory incisional/excisional biopsy; cannot replace tissue biopsy
• Indications: initial screening of suspicious white/red lesions, monitoring multiple sites, patients who refuse surgical biopsy

5. Punch Biopsy

• A circular punch instrument (2-6 mm) is used on oral mucosal lesions
• Best suited for the hard palate and sites where mucosa is bound down (not freely movable)
• Heals by secondary intention
• Produces a comparable specimen to scalpel biopsy but may be technically difficult on mobile oral tissues
• No proven advantage over scalpel biopsy in the oral cavity

III. Based on Instrument / Material Used

IV. Based on Clinical Timing

V. Based on Anatomical Site / Tissue Type in Oral Region

VI. Based on Purpose

Decision Algorithm - Which Biopsy to Choose?

Oral lesion persisting >2 weeks
        ↓
Fluid-filled / intraosseous radiolucency?
        ↓ YES → Aspiration biopsy first
        ↓ NO
Size ≤1 cm, clinically benign?
        ↓ YES → Excisional biopsy
        ↓ NO
Lesion >1 cm / suspected malignant / diffuse borders?
        ↓ → Incisional biopsy (from margin, not centre)
Neck mass / parotid swelling?
        → FNAB
Surface screening / patient refuses surgery?
        → Brush biopsy / exfoliative cytology (confirmatory biopsy still needed)

Key Rules in Dental Biopsy (Surgical Principles)

1. Always aspirate intraosseous lesions before cutting into bone - avoids catastrophic haemorrhage from vascular lesions
2. Never biopsy from the necrotic centre - sample from the active periphery/margin
3. Avoid electrocautery and laser for biopsy incisions - they distort histological architecture
4. Block anaesthesia preferred over infiltration into the lesion (avoids distorting tissue planes)
5. Narrow and deep > broad and shallow - depth gives better information about invasion
6. Orient the specimen for the pathologist with sutures or notches
7. Fix immediately in 10% buffered formalin (unless sending for frozen section or microbiological culture)
8. Lesion orientation diagram should accompany every specimen submitted

• Oral Biopsy in Dental Practice, Mota-Ramírez A et al., Med Oral Patol Oral Cir Bucal 2007
• Biopsy in Oral and Maxillofacial Surgery, University of Mosul / MUC Lecture Series 2025
• Oral Tissue Biopsy: Overview, Medscape eMedicine