Punch biopsy

Indication — inflammatory dermatoses, suspected non-melanoma skin cancer for subtyping, large lesions where representative sampling is acceptable.
3–4 mm punch most commonly used; 6 mm where adequate dermis is needed (e.g. panniculitis).
Local anaesthesia with 1% lidocaine + adrenaline 1:200 000 (avoid digits and end-arteries — use plain lidocaine).
Skin tensioned perpendicular to relaxed skin tension lines so the resulting defect is elliptical and easier to close.
Specimen handled by the deep edge with toothed forceps — avoid crush of the diagnostic surface.
Closure method depends on size, site and tension; small trunk punches can be left to heal by secondary intention.
Do not punch the centre of a pigmented lesion suspicious for melanoma — depth assessment will be lost. Use excisional biopsy.

Shave biopsy

Indication — clearly benign exophytic lesions (seborrhoeic keratoses, naevi for cosmesis), suspected superficial BCC for subtyping, AK with diagnostic uncertainty.
Contraindication — any pigmented lesion where melanoma is plausible (Breslow depth lost).
Use 15-blade scalpel or a flexible razor blade.
Saucerisation (deeper shave) is used for some BCC subtyping and superficial cSCC; depth must allow assessment of the dermis.
Haemostasis with aluminium chloride, ferric subsulphate or light electrodesiccation.
Heal by secondary intention; outcome depends on site (concave better than convex).

Indication — large lesions where excision would cause unacceptable morbidity before histology, suspected inflammatory or infiltrative process, lymphoma, suspected sarcoma.
Take a longitudinal ellipse oriented along the future definitive excision axis so the scar can be re-excised within the definitive specimen.
Include lesion-skin junction and adequate dermis ± subcutis.
For suspected sarcoma the biopsy should be discussed with the regional sarcoma MDT before sampling — incorrectly placed biopsies can mandate larger definitive excisions.

Indication — pigmented lesions suspicious for melanoma; small atypical lesions where complete histology is required.
2 mm peripheral margin recommended for suspected melanoma (NICE NG14 §1.3) — preserves Breslow accuracy and avoids transection.
Cuff of subcutaneous fat at the deep margin is essential.
Orient the long axis along relaxed skin tension lines unless re-excision likely to require a specific axis (e.g. lower limb — longitudinal).
Mark the specimen for orientation (suture at 12 o'clock) where re-excision of an asymmetric margin may be planned.
Send formalin-fixed, with brief clinical history and a precise anatomical location on the request slip.

Pigmented lesion + shave biopsy = diagnostic disaster if melanoma — always excisional.
Document the biopsy site photographically — patients often cannot identify it themselves at follow-up.
"Site marking" with a sterile pen, suture-on-skin photograph, or a triangulating photograph relative to a landmark prevents wrong-site wide excision.
Specimen orientation — suture or ink a margin only where it would influence re-excision of a single involved margin; over-orientation creates pathology confusion.
Always include patient identifiers and clinical history on the request form; "?BCC" is inadequate — provide age, immune status, prior cancers, anatomical site.