Eyelid skin cancer diagnosis: what Mohs surgery and eyelid reconstruction involve

A biopsy result that says basal cell carcinoma, on an eyelid, arrives with a great deal of fear and very little explanation. Most of the fear comes from two words: cancer, and eyelid. The next steps are more ordered than the first phone call makes them sound. Here is what the surgery involves, how the eyelid is rebuilt, and what the studies say about recurrence and complications.

What does a basal cell carcinoma result on my eyelid mean?

It means a biopsy, a small piece of tissue sent to the laboratory, has shown a skin cancer that starts in the basal cells of the skin. Basal cell carcinoma is the most common malignant tumour of the eyelid in the Malaysian data I could find: a five-year review of 136 eyelid biopsies at Hospital Sultanah Bahiyah in Alor Setar, from 2016 to 2020, found it the most frequent malignant tumour, and 81.8% of the malignant tumours were on the lower lid. The abstract and the tables of that paper disagree on the exact number of basal cell cases, so I will not quote a count.

Abroad the pattern is similar. A Swedish series notes that the periocular region accounts for about 20% of all basal cell carcinomas, and a Brazilian series of 108 patients found the lower eyelid the commonest site (55.5%), followed by the inner corner of the eye, the medial canthus (29.7%). The recognition side is in my article on eyelid skin cancer warning signs. This one starts after the diagnosis. The action is the same for everyone: this needs treatment by a team used to eyelids, and the plan is decided after examination.

What is Mohs surgery, and why is it used on eyelids?

Mohs micrographic surgery removes a skin cancer in thin layers and checks each layer under the microscope while you wait, until the edges are clear. The British Association of Dermatologists describes it as a special type of skin surgery used to remove skin cancers, most commonly basal cell carcinomas. It is recommended where the edges of the cancer are hard to see, and in sensitive areas including the eyelids, nose, ears and lips. It is also used for large or recurrent cancers.

The reason that suits an eyelid is simple. An eyelid has very little spare tissue, and every millimetre of it protects the eye. That is my reading of why the guidance lists it among the sensitive sites. The area is numbed with a local anaesthetic, which the leaflet says may sting at first and settles within 30 seconds or less.

How is Mohs different from ordinary excision, and who does which part?

In ordinary excision the surgeon cuts out the cancer with some surrounding healthy skin. The NHS calls surgery the main treatment for non-melanoma skin cancer, and says a skin graft may be needed after larger removals. In Mohs surgery the margin checking happens during the operation, in stages, and the wound is closed only when the layers come back clear. That is why the visit can be long: the leaflet says results can take up to 3 hours, and some people stay in hospital up to a day.

The leaflet lists five ways to repair the wound: letting it heal naturally, stitches, a skin graft, a skin flap, or referral to another surgical team to reconstruct the wound. That last one matters for eyelids. The person who removes the cancer and the person who rebuilds the lid may be two different specialists, or one, and it is reasonable to ask at the start who will do each part. I have no source on how Mohs surgery is organised in Malaysia, so I will not describe local services, and a referral letter from a GP is a practical place to start.

How many stages are needed varies. The BAD says that in 90% of cases the skin cancer is removed after 1 to 2 stages. In the Swedish series of 167 patients with periocular basal cell carcinoma, 33% needed one stage, 46% two and 17% three, and the rest four to six. A larger tumour tends to need more: in the Brazilian series, tumours over 10 mm went with aggressive histology, more stages and more complex reconstruction.

What does eyelid reconstruction involve?

It means rebuilding what was removed so the lid protects the eye, keeps the tears draining and looks acceptable. One review puts it exactly that way: the reconstructed eyelid must protect the ocular surface, maintain lacrimal drainage, and achieve an aesthetically acceptable result. That is a different aim from closing a cut anywhere else on the body.

The eyelid is built in two layers, and both may need rebuilding. The front layer, the anterior lamella, is the skin and the orbicularis muscle, the ring of muscle that closes the eye. The back layer, the posterior lamella, is the tarsus, the firm plate that gives the lid its shape, and the conjunctiva, the lining that touches the eye. When the whole thickness of a lid is removed, both layers are replaced, often with different materials.

Small defects may be left to heal or closed with stitches. Larger ones may need a flap, in which nearby skin is moved with its blood supply, or a graft, in which skin is taken from elsewhere. In the Swedish series the commonest lower-lid reconstruction was a full-thickness skin graft with flaps. For big defects a tarsoconjunctival flap such as the Hughes flap is commonly used for large defects and needs two operations, with the eye kept closed for 3 to 6 weeks in between. Frail older patients may be offered single-stage options with less risk, as one case report describes. That report is one 84-year-old patient, so it shows a possibility and not a rule. Which method suits which defect is decided by the size, the site, and the person's health.

How will my eyelid look and close afterwards?

Most people in the studies did not have a complication, but enough did that it should be discussed before surgery. In the Swedish series 62 of 167 patients (37%) had one, and the commonest was cicatricial ectropion in 11.4%. Cicatricial ectropion is a lower lid pulled away from the eye by scar, which leaves the surface exposed and the eye watering; my article on ectropion explains it. A review of reconstruction adds that full-thickness skin grafts can shrink, and can differ in colour from the skin around them.

Protecting the eye surface is the point of the reconstruction, and what happens when a lid does it poorly is covered in dry eye after eyelid surgery. The BAD lists bleeding, bruising and scarring as the common risks and infection, nerve damage and recurrence as less common. I cannot give a picture of what a particular lid will look like, and I will not use before-and-after images to try. What I can say is that the aim is a lid that closes, drains and protects, and that a lid pulling away from the eye is a reason to go back to the surgical team.

Will it come back, and what follow-up is needed?

It can, and the studies followed people for years for that reason. In the Swedish series there were nine recurrences (5.4%) after a mean of 37 months, and every one was in a tumour that was already a recurrence when it was treated. The Brazilian series found recurrence in 3.8%, with a mean follow-up of 64.8 months. These are figures for groups treated at specialist centres, and they describe the past. They are not a promise for any one person.

After Mohs surgery the BAD says you get aftercare appointments for dressing changes or stitch removal. The longer-term schedule is for the treating team to set, and the two series above followed patients for at least 5 years and for a mean of 64.8 months. The NHS advice on non-melanoma skin cancer is to seek medical attention for a growth or area of skin that hurts, itches, bleeds, crusts or scabs for more than 4 weeks.

If you are unsure about the plan, a second opinion before eyelid or orbital surgery is a normal request. Dr Ong Jin Khang of The Retreat Clinic explains, from the skin side, why an eyelid lesion is not a pigment target and needs diagnosing first. The rest of the lid conditions are under eyelid conditions, and the wider picture is in the guide to what makes eyes look tired.