Cutaneous metastases: cancer that has spread to the skin

Metastases are secondary cancers: deposits that have grown from cells which broke away from the original, or primary, tumour. The Primary Care Dermatology Society (PCDS) explains that skin metastases can result from spread from an internal cancer or from a skin cancer, usually melanoma. Breast Cancer Now stresses that, for breast cancer, the cells in the skin are still breast cancer cells and are treated as such, rather than being a new skin cancer.

Breast Cancer Now says breast cancer cells reach the skin through the lymphatic system or the blood. The PCDS also describes cancers that grow directly into the skin from an underlying tumour, most often breast cancer, which can present with distinct patterns such as skin inflammation, a morphoea-like hardening or an orange-peel appearance.

The PCDS gives the generally accepted order of frequency as breast, skin (melanoma), lung, colon, stomach, upper aerodigestive tract (nasal sinuses, larynx, oral cavity), kidney and uterus. When skin metastases arise from a previously unknown primary tumour, it says the most common origins are kidney, lung, thyroid and ovary.

Where the lumps appear tends to reflect the source. The PCDS says most occur in a body region near the primary tumour: for example the chest from breast, lung or melanoma; the abdomen from colon, lung, stomach, breast or ovary; and the scalp from breast, lung or kidney. A nodule at the umbilicus, called Sister Mary Joseph's nodule, can come from stomach, colon, ovary, kidney or breast.

The PCDS says patients may present with a rapidly developing nodule or subcutaneous nodule, single or multiple. Nodules are often round or oval, firm, mobile and rubbery, and usually flesh coloured, though they may be red-purple, brown or blue-black. It says they are asymptomatic in most instances, although pain and tenderness may be noted.

Breast Cancer Now lists a change in the colour of the skin, a lasting rash, and a firm, painless, small lump (nodule) or several lumps of different sizes. It says redness and inflammation may look like an infection of the skin called cellulitis. Other possible symptoms include pain, bleeding and infection, which can cause an unpleasant smell if the skin has broken down, and lymphoedema, swelling of the arm, hand or breast area. For breast cancer, the most common places are the chest wall, around the surgical scar or the tummy, and less commonly the scalp, neck, back and arms.

Anyone with a past cancer diagnosis who notices a new, firm or changing lump, a lasting rash or a skin change near a scar should tell their cancer team or GP promptly rather than waiting for the next routine check. Most skin lumps are not cancer, but if one is, it needs to be identified. If an area of skin is bleeding heavily, becoming rapidly red, hot and swollen with a fever, or you feel unwell, seek urgent advice through NHS 111 or your cancer team's emergency number.

Breast Cancer Now says your treatment team will examine you and look at your skin and discuss any other symptoms. To confirm a diagnosis of secondary breast cancer in the skin you may have a punch biopsy, which takes a very small circle of tissue after a local anaesthetic, with a small dressing applied after. You may also have a CT scan to check for signs of spread to other parts of the body, which takes around half an hour and may involve dye injected into a vein.

The PCDS notes that in the rare cases where skin metastases occur at the same time as, or before, the primary cancer is diagnosed, they may be the prompt for a thorough investigation to find the primary.

Breast Cancer Now says the treatment you are offered depends on your symptoms, the type and features of the cancer, whether it has spread to other areas, previous treatments and your general health. The aim is to relieve symptoms, improve quality of life and slow the growth of the cancer. Treatments can be given alone or together.

Breast Cancer Now explains that electrical impulses open pores on the surface of cancer cells in the treated area for a short time, so the chemotherapy drug enters the cells more easily and is sealed inside once the pores close. The chemotherapy dose is much lower than when given to treat the whole body, and the treatment will not treat other areas of secondary cancer inside the body.

Several tests may be needed first, such as blood tests, a chest X-ray, a CT scan of the chest and lung function tests, and it may not be suitable for some people with certain lung conditions. You may need to travel to a different hospital to have it. The procedure usually takes between 10 and 60 minutes depending on the size of the area, under local or general anaesthetic.

Breast Cancer Now says that as treatments have improved more people are living much longer after a diagnosis of secondary breast cancer, but that life expectancy is difficult to predict, and no two cancers progress or respond to treatment in the same way. Because each person's case is different, the team looking after the original cancer is the right place to ask what to expect.

Skin changes can be distressing, especially if they are visible, bleed or smell. Tell your team about these symptoms: Breast Cancer Now lists specialist dressings, pain relief and antibiotics among the supportive treatments available,.

Skin metastases are assessed and treated by your oncology team on the NHS, with dermatology, radiotherapy and palliative care involvement as needed. Breast Cancer Now notes you may need to travel to a different hospital to have electrochemotherapy. Private oncology and dermatology consultations can offer a quicker assessment or a second opinion, and biopsies, radiotherapy and drug treatments are the same procedures in both sectors.