Vulval biopsy

What is vulval biopsy?

Vulval (or vulvar) biopsy involves taking a sample of tissue from the vulval skin or muscosal membranes.

When is vulval biopsy undertaken?

Vulval biopsy may be appropriate when:

• Malignancy is suspected
• An autoimmune blistering disorder is suspected
• Lesions have atypical vascular patterns, pigmentation or texture
• Condition has not resolved with standard treatment
• Results have implications for the diagnosis and management of systemic illness or serious local disease (eg, Behcet disease, Crohn disease)
• Removal of a lesion is requested for functional or aesthetic reasons

Typical vulval conditions that undergo biopsy include:

• Lichen sclerosus
• Lichen planus
• Squamous intraepithelial lesions
• Vulval squamous cell carcinoma
• Melanoma

What are contraindications to vulval biopsy?

There are no absolute contraindications to vulval biopsy.

Relative contraindications include:

• Infection at the site (although this may also be a reason for biopsy)
• Bleeding tendency
• Recent (< 3 weeks) attempts to chemically destroy a lesion
• Allergy to local anaesthetic

Pre-biopsy considerations

Site selection

• Biopsy of the clitoris, urethra and rectum should be avoided unless absolutely necessary
• Ensure biopsy includes the lesion edge in potential inflammatory or neoplastic processes, ulcers and pigmented lesions
• For large or non-uniform lesions, multiple biopsies may be required

Depth of biopsy

• Vulvar dermis thickness varies: it is thinnest on the vestibule and thickest on the hair-bearing skin (normally no more than 4 mm)
• Disease of hair-bearing areas can extend into the hair shaft thus requires deeper sampling, preferably down to subcutaneous fat
• In non-hair-bearing areas, 1–2 mm depth is usually adequate
• Lesions suspected to be neoplastic should undergo deep biopsy to assess invasion.

Reducing patient discomfort

The vulvar skin and mucosa is highly sensitive, and injection with even a small-gauge needle is painful.

To minimise general patient discomfort:

• Provide oral analgesia (paracetamol, ibuprofen) taken at least 30 minutes before the procedure
• Consider topical anaesthesia for superficial dermatoses requiring minimal depth biopsy, or prior to infiltration of local anaesthetic
• Lidocaine-prilocaine water-emulsion (EMLA; eutectic mixture of local anaesthetics) is a topical anaesthetic that causes dermal and mucosal analgesia to needle prick within 15–30 minutes.

To minimise stinging associated with infiltration of local anaesthetic:

• Warm the solution to body temperature
• Buffer the solution with 8.4% sodium bicarbonate (1 mL sodium bicarbonate to 10 mL anaesthetic solution)
• Inject the solution slowly with a small-gauge needle (eg, 27 or 30 gauge).
• Clean the area with a topical antiseptic such as iodine or chlorhexidine solution.
• Elevate the lesion by subepidermal infiltration of 1% lignocaine (+/- adrenaline to reduce bleeding and prolong anaesthetic effect).
• Consider direction of the skin tension lines when marking out biopsy site.

Vulval biopsy procedure

The most common types of vulvar skin biopsy are shave or snip biopsy, punch biopsy, incisional or excisional biopsy.

Shave or snip biopsy

• Useful for raised or pedunculated lesions (eg, skin tags, small condyloma acuminata, dermal melanocytic naevi).
• Performed with a #15 surgical blade scalpel, or curved scissors if slightly greater depth is required.
• When a scalpel is used, the lesion is elevated and removed with a single sweeping motion.
• When curved scissors are used, the lesion is elevated then excised with scissors pointing upwards.

Punch biopsy

• Useful for biopsy of superficial inflammatory dermatosis or bullous disease, excision of small pigmented lesions, or when it is important to determine lesion depth.
• A cylindrical dermal punch (eg, Keyes biopsy punch, usually 3–5 mm diameter) is used to perform a full-thickness skin biopsy.
• Stretching the skin perpendicular to the tension lines with the non-dominant hand, apply the cutting edge of the punch and rotate with light pressure until the desired depth is reached.
• The resulting tissue sample is gently lifted with forceps and cut from the underlying subcutaneous tissue with curved scissors.
• When the skin is released, the circular defect will relax into an ellipse allowing the wound to be closed more easily.
• Once haemostasis is obtained, the wound can be closed using one or two sutures.
• NOTE: in cases of possible autoimmune blistering diseases, a second sample or half of a single larger sample should be sent for direct immunofluorescence.

Incisional biopsy

• Useful for sampling a large lesion without leaving a large tissue deficit.
• Involves removing an elliptical sample of a lesion using a scalpel, and closing the wound with sutures once haemostasis is obtained.

Excisional biopsy

• Once haemostasis is obtained, the wound can be closed using one or two sutures.
• Used to remove a tumour, such as an atypical pigmented lesion.
• Involves complete removal of a lesion using a scalpel, closing the wound with sutures once haemostasis is obtained.
• Marking an ellipse on the tissue prior incision ensures symmetry and thus easily opposable edges for suturing.

Completing the request form

Ensure each specimen is placed in a separate container and correctly labelled with name, date and biopsy site along with a request form prior to transport for processing. Note that although most specimens are transported in 10% formalin as a fixative, direct immune fluorescence and frozen section testing will require fresh specimens.

Haemostasis

Any bleeding can be stopped in a variety of ways depending on the nature of the biopsy:

• Direct pressure may be adequate for small punch or shave biopsies
• Chemical haemostasis with silver nitrate sticks, aluminium salt solution or Monsel solution
• Electrocautery
• Physical haemostasis with sutures.

Suture choice includes monofilament nylon (which must be removed 5–7 days after the procedure) and absorbable braided fibre.

Most vulval biopsies are not covered given the difficulty of keeping a dressing in place, however a pantyliner may be useful to protect the area and to absorb any ooze or bleeding.

Post-biopsy care

• Ensure adequate analgesia, eg, paracetamol, ibuprofen, cold compresses.
• In case of bleeding, apply direct pressure over the biopsy site.
• After urinating, use a bottle filled with warm water to wash the area then gently pat dry.
• Avoid baths, hot tubs and swimming pools until the wound has healed completely.
• Avoid sexual intercourse and cycling until discomfort has resolved (usually 3–5 days).
• Wear loose cotton underwear and avoid tight pants to reduce friction.
• Healing usually occurs in 5-7 days, but may take longer depending on the depth of deficit.
• In case of worsening pain, swelling, spreading redness, malodorous discharge from the wound, or fever, seek urgent medical attention.

What are the benefits of vulval biopsy?

• Biopsy provides a more definitive diagnosis of lesions that cannot be identified by history, and examination.
• It can help determining appropriate management for treatment-refractory skin diseases.
• It enables removal of a lesion.

What are the disadvantages of vulval biopsy?

• Pain
• Infection
• Bleeding, haematoma or bruising, particularly in those with bleeding tendencies or on blood-thinning medications
• Scarring or hypopigmentation
• Hyperpigmentation/iron staining from Monsel solution (usually temporary)
• Inadequate sample, possibly requiring further biopsy
• Allergic contact dermatitis to topical antiseptic, anaesthetic, suture material or dressings
• Persistence or recurrence of the vulval lesion