Extramammary Paget Disease, from the CureRays guide library.

Extramammary Paget disease is a slow-growing skin cancer of sweat-gland-rich areas like the groin; it spreads in the top layer of skin, and radiation can cure it when surgery can't.

What it is.

Extramammary Paget disease (EMPD) is an uncommon cancer that grows within the upper layer of skin in areas dense with apocrine sweat glands — most often the vulva, scrotum, penis, groin, or around the anus. It usually appears as a red, scaly, itchy patch that is mistaken for eczema or a fungal infection for months or years. Most cases stay confined to the skin surface (in situ) and are slow-moving, but the disease tends to extend microscopically well beyond the visible patch, which makes complete removal difficult and recurrence common. In a minority, it becomes invasive or signals an underlying internal cancer, so evaluation looks for both.

How radiation treats it.

Radiation delivers focused energy that damages the DNA of the abnormal skin cells so they can no longer divide, clearing the patch over the weeks following treatment. EMPD is well suited to radiation because the disease lives in the skin where a broad, even surface dose can cover the wide microscopic spread that makes surgery hard. The beam is shaped to the affected area — useful in the groin and genital region where surgery can be disfiguring — and given as a series of short, painless daily sessions. The main side effect is a temporary skin reaction in the treated area.

The ways we can treat it.

Definitive (radical) radiation. For inoperable disease or patients who decline surgery, external-beam radiation to the affected skin (often 60-70 Gy) can control or cure the tumor while preserving sensitive anatomy.

Adjuvant radiation. Given after surgery when margins are positive or the disease keeps recurring, treating the broad at-risk skin field that surgery may have missed.

Nodal radiation. When lymph nodes are involved, the draining groin nodes are included; treating only the skin and ignoring at-risk nodes is linked to worse outcomes.

Questions we hear often.

I was told it looked like eczema for a long time — is that normal? Yes. EMPD is famous for mimicking eczema or a fungal rash, so diagnosis is often delayed. A skin biopsy of a patch that won't clear with creams is what makes the diagnosis.

Can radiation cure it without surgery? It can. For people who aren't good surgical candidates or who want to avoid disfiguring surgery in the genital area, radiation alone can control or cure the disease, and it's also used after surgery for stubborn cases.

Why are my doctors checking for another cancer? A minority of EMPD cases are linked to an underlying gland or organ cancer (secondary EMPD). Checking for one ensures the whole problem is treated, not just the skin patch.

This guide is informational only. It is not medical advice — please confirm anything here with your care team.