Understanding Skin Cancer Margins — What “Clear,” “Close,” and “Positive” Mean

Why Margins Matter

Margins matter because they are the only way to confirm — under the microscope — that all cancer cells have been removed. Even when a lesion looks completely excised to the naked eye, tiny clusters of cells can extend just beyond the visible edge.

Pathologists measure how close cancer cells come to the inked border of the specimen:

• Clear margins mean there’s a safety zone of normal tissue — a strong sign the cancer is completely gone.
• Close or involved margins mean cells reach the edge or are only fractions of a millimetre away, which increases the risk of the cancer growing back in the same spot.

Research consistently shows that rates of the cancer returning (recurrence) are far lower when margins are clear and of adequate width. That’s why the recommended margins used for skin cancers differs for each cancer type — smaller for slow-growing BCCs, and wider for faster growing cancers like SCC or melanoma.

The aim is always to remove enough tissue for complete safety while preserving as much healthy skin as possible for optimal healing and appearance.

Different Cancers, Different Margins

Basal Cell Carcinoma (BCC) – Common but Persistent

BCC is the most common type of skin cancer. It tends to grow slowly and rarely spreads to other parts of the body. However, if it’s not completely removed, it can gradually burrow into nearby skin and tissues.

To make sure every part is cleared, surgeons usually remove about 2–3 mm of normal-looking skin around it. More aggressive or recurrent BCCs may need a slightly wider margin.

Because BCCs often occur on the face, the surgeon plans the incision carefully — aiming to remove all the cancer while keeping scars as discreet as possible.

Think of it like removing a weed — you don’t just take the leaves, you take a small ring of soil around the roots to stop it from coming back.

Squamous Cell Carcinoma (SCC) – Can Grow Quickly and Spread

SCC is generally faster-growing than BCC and can sometimes spread to nearby lymph nodes if not fully removed. To keep that risk very low, surgeons remove a wider rim of skin — usually 4–6 mm or more for high-risk or deeper SCCs.

Most SCCs are cured with one operation, and the additional margin is “insurance” against it returning.

Melanoma – Why Margin Width Matters

Melanoma is more serious because it can spread if left untreated. Even when the visible spot is removed, melanoma cells can extend a few millimetres beyond what’s seen on the skin — almost like invisible roots. That’s why surgeons remove an extra rim of normal skin around it.

The width depends on how deep the melanoma goes under the microscope:

• 2 cm for thicker ones
• 1 cm for thinner melanomas

These recommendations are based on decades of research, including work by Dr Varun Harish FRACS, published in the Journal of Plastic, Reconstructive & Aesthetic Surgery (doi:10.1016/j.bjps.2013.04.032), which is cited in Australian melanoma guidelines.

The goal is simple: remove enough tissue for complete safety while keeping as much healthy skin as possible for a good functional and cosmetic result.

What Happens After Surgery & How Margins Are Checked

After removal, the specimen is precisely labelled and marked with a stitch so the pathologist knows its orientation. It’s then set in wax, sliced thinly and examined under the microscope: a process called standard paraffin histology. Margins are measured from the cancer to the edge of specimen in millimetres (e.g. “3 mm clearance”) and results are usually ready in a few days.

In certain cases, a frozen section test may be done whilst you’re still having the procedure. A tiny sample from the wound edge is rapidly frozen and checked immediately. If any cancer cells are seen, a little more tissue is removed on the spot. Frozen section helps avoid another operation when tissue preservation is critical, but for most patients the detailed paraffin report remains the gold standard.

Learn more about how skin cancers are removed and reconstructed on our Skin Cancer Surgery page.

Understanding Your Pathology Report

Your pathology report often aims to answer one question — is it all out?

Report Term	What It Means
Clear margin	No cancer cells near the edge – fully removed.
Close margin	Cells come very near the edge – additional treatment may be advised.
Positive / involved margin	Cells reach the edge – additional treatment may be advised.

The Different Components of a Pathology Report (and What They Mean)

A pathology report is much more than a simple yes or no result. It summarises everything the pathologist saw under the microscope and guides your treatment. Most reports include several key sections. Many people find the medical language in pathology reports confusing — it’s completely normal to ask your surgeon to explain each part.

Report Section	What It Tells You
Patient & Specimen Details	Confirms your details, the site of the lesion and when the sample was received.
Clinical Information	Notes from your surgeon describing the suspected type of cancer, its precise location and whether it’s a first or recurrent cancer.
Diagnosis	The official name of the cancer – e.g. nodular BCC, invasive SCC or superficial spreading melanoma.
Tumour Subtype	Identifies the specific pattern or variant, which can affect how wide a margin is needed.
Margins	How far cancer cells are from the specimen edge, measured in mm.
Depth / Thickness	How deep the cancer extends below the surface. In melanoma this is the Breslow thickness, which guides the safety margin.
Degree of Differentiation	Describes how abnormal the cancer cells appear. Well-differentiated cancers behave more like normal skin and are generally less aggressive. Poorly differentiated cancers look very abnormal and may behave more aggressively or have a higher risk of spreading.
Perineural or Lymphovascular Invasion	Indicates that some cancer cells were found near small nerves or within tiny blood or lymph vessels. These findings help your surgeon assess whether extra treatment or closer follow-up is needed.

If any of these terms appear in your report, your surgeon will explain what they mean for you personally. Not every technical term changes your care.

Mohs Surgery – One of Several Options

Mohs micrographic surgery has its place in certain cases, particularly where conserving healthy skin is critical. However, it also has some limitations:

• Each layer must be processed, so appointments can take several hours.
• It often involves a dermatologist to remove the cancer and a plastic surgeon to reconstruct the area later, sometimes the next day.
• Multiple doses of local anaesthetic may be required.

Standard excision and reconstruction performed in a single procedure achieve excellent cancer clearance for most patients. Learn more about our comprehensive skin-cancer surgery service.

Why Evidence and Teamwork Shape These Rules

Modern skin-cancer care is built on research and collaboration. The recommended margins used today come from years of international studies confirming how much healthy skin should be removed to prevent recurrence.

Dr Varun Harish has contributed to this work through published research on melanoma excision margins  and complex skin cancer management, which have informed current treatment guidelines. This evidence-based approach guides how each operation is planned — balancing safety with the cosmetic and functional outcomes.

He also participates in multidisciplinary melanoma and skin cancer meetings at Royal North Shore and the Liverpool Hospitals, part of the state-wide multidisciplinary cancer care network .
These meetings bring together surgeons, dermatologists, oncologists and pathologists to ensure every plan reflects current best practice and is tailored to each patient’s situation.

Behind every decision — from margin width to reconstruction — is collective expertise supported by research and teamwork.

Reassurance and Recovery

Most patients heal quickly. Stitches are removed after 1–2 weeks; scars soften and fade over months.

If a second small procedure is needed, it’s usually performed a few weeks later.

Once clear margins are confirmed, recurrence in that spot is rare. Regular skin-checks and surveillance remain the best safeguard for long-term health. If a scar remains noticeable later, options such as scar revision surgery can further refine its appearance.

Key Takeaways

• Margins = the thin rim of healthy skin removed with the cancer.
• Clear margins = complete removal in nearly all cases.
• Different cancers need different margins – smaller for BCC, wider for SCC and melanoma.
• Pathology margins are the final checkpoint confirming your cancer has been safely and completely removed.
• Team-based, evidence-guided care aims to achieve the best outcomes for skin cancer.

Frequently Asked Questions

About Dr Varun Harish FRACS

Specialist Plastic, Reconstructive & Burns Surgeon
Consulting in St Leonards on Sydney’s North Shore, serving patients across the Northern Beaches, Inner West and Central Coast.
Active member of the Royal North Shore and Liverpool Hospital Cancer Teams.
Published author on melanoma margins and complex skin-cancer management in peer-reviewed journals.