Bowen's disease

Bowen's disease is the earliest stage of squamous cell skin cancer. The altered cells are already there, but they remain confined to the surface layer of the skin and cannot reach the blood or the lymph, so they do not seed other organs. It looks like a persistent reddish, scaly patch with a clear edge that has failed to heal for months and does not respond to creams. Treatment is straightforward and almost always clears it completely. The real difficulty lies not in treating it but in the fact that such a patch is taken for eczema or psoriasis for years.

What the patch looks like and where it appears

The patch grows very slowly, sometimes over years, and barely changes from week to week. Typically it is:

• flat or slightly raised, covered with scale or a thin crust;
• anything from a few millimetres to several centimetres across, with a sharp, well-defined edge;
• red or pink on pale skin; on brown and black skin it tends towards brownish or greyish-violet and is far harder to spot;
• sometimes mildly itchy, though more often it causes no trouble at all.

There is frequently more than one patch. They appear where the sun has been landing for decades: the lower legs, the face, the ears, the neck, the scalp in men with thinning hair, and the backs of the hands.

The form that arises in the groin and on the external genitals, including the head of the penis, deserves separate mention: there the patch tends to be moist, bright red and glistening, and the usual cause is different — human papillomavirus. Another unusual variant affects the skin around a nail and is easily mistaken for inflammation that will not settle.

How dangerous it is

On its own such a patch is not life-threatening and is no reason to panic. The danger is different: left untreated, the altered cells may eventually grow down into the deeper layers, and at that point it becomes a genuine squamous cell cancer, capable of spreading. This happens in roughly three to five people in a hundred with untreated Bowen's disease, and usually only after years.

The risk is higher for patches on the genitals and in people whose immunity is suppressed. And to settle a common fear: Bowen's disease has nothing to do with melanoma — different cells altogether, and a completely different outlook.

When not to wait

See a doctor promptly if a familiar patch starts behaving differently:

• a firm nodule or a thickening appears within it;
• it starts to bleed, or turns into an ulcer that will not close;
• pain or tenderness on touch develops;
• it begins to grow noticeably after years of staying the same;
• a nearby lymph node enlarges.

These are signs that the process has gone beyond the surface layer of the skin, and it needs sorting out faster.

There is one more situation that explains why the condition is so often found late. If an area of skin being treated as eczema or psoriasis has not responded to a steroid cream within four to six weeks, while the other patches have, that one patch should be shown to a dermatologist separately.

What leads to Bowen's disease

The main cause is sun accumulated over a lifetime, not one bad burn. That is why the condition turns up mostly after sixty, in people with fair skin, in those who worked outdoors for years, and in users of sunbeds.

What else raises the odds:

• suppressed immunity — the medicines taken after an organ transplant, treatments that damp down the immune system, HIV infection;
• radiotherapy in the past, with the patch appearing years later within the treated field;
• human papillomavirus, in the case of patches in the groin and on the genitals.

There is also an uncommon cause worth knowing about: long-past exposure to arsenic, whether through medicines of an earlier era, water from contaminated wells, certain industries or pesticides. Those patches appear decades later, tend to be multiple and sit in places the sun never reaches, and small hard nodules are often visible on the palms and soles. If the picture fits, it matters that the doctor is told: arsenic raises the risk not only of skin tumours but of internal ones, and the assessment then needs to be broader.

Bowen's disease is neither catching nor inherited.

Why an exact diagnosis matters

The patch is easily confused with eczema, psoriasis, a fungal infection, a seborrhoeic wart, an actinic keratosis or a superficial basal cell carcinoma. The difference between them is fundamental and is not always visible to the naked eye: even an experienced dermatologist examines such a patch through a dermatoscope.

Only a biopsy gives a reliable answer: under local anaesthetic a small piece of skin is taken and studied under the microscope. The procedure is short, and its result determines everything that follows.

Hence a warning: do not spend months treating an unexplained patch with a steroid cream bought on someone's recommendation. It dulls the redness and blurs the picture without touching the altered cells, and the time is lost.

How it is treated

There are several options and all of them work. The choice depends on the size of the patch, where it sits, and how well wounds heal in that spot.

• Cryotherapy — treatment with liquid nitrogen. Quick, though it stings during the session; a crust then forms and comes away over a few weeks.
• Creams containing fluorouracil or imiquimod, applied in a course lasting several weeks. The skin will inevitably redden and become inflamed: that is the expected course of treatment, not a complication, and it is not a reason to stop.
• Curettage with cautery under local anaesthetic: the altered area is scraped away and the wound heals under a scab.
• Photodynamic therapy — a light-sensitive preparation is applied and, some hours later, the skin is lit with a special lamp. The cosmetic result is good.
• Surgical excision is used when the diagnosis is in doubt or invasion into the deeper layers is suspected.

Sometimes simply watching is the right answer. In an older person with a slowly growing patch on the lower leg, a doctor may conclude that the harm of treatment would outweigh the benefit — that is a reasoned decision, not a refusal to help.

The lower legs deserve a word of their own. Skin there heals badly, especially with swelling, diabetes or poor circulation, and treatment pressed too hard can leave an ulcer that will not close. That is why the method chosen for the legs is weighed more carefully than for the face or the hands.

What to do after treatment

Your doctor will arrange a follow-up to confirm that the skin has healed and that no further treatment is needed. Stitches, if there was surgery, come out after a week or two; sometimes dissolvable ones are used. Dressings are changed as you are advised.

Without waiting for that appointment, go back if a thickening appears at the site of the old patch, if it bleeds or changes in appearance, and also if you notice new, similar patches elsewhere on your skin.

New patches are entirely possible, and they do not mean the treatment failed: the sun damaged not one spot but all the exposed skin. From here on, two things count.

• Sun protection: covering clothes and a hat, shade in the middle of the day, and a sunscreen of factor 30 or above on the face, ears, neck and hands all year round. Sunbeds are out entirely.
• Checking your own skin every month or six weeks, with a mirror, not forgetting the ears, the scalp, the backs of the hands and the lower legs. Any patch lasting more than a month is worth showing to someone.

Online consultation

In an online appointment the doctor will ask how long the patch has been there and how it has changed, use your photographs to judge how typical the picture is, review the risk factors — sun, medicines that suppress immunity, past radiotherapy — explain when a biopsy is needed and which specialist to see, and help you make sense of a report you already have and of skin care after treatment.

This material is for information only and does not replace medical advice.