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Skin Signs of Internal Cancers

Skin disorders may be indications of internal bodily conditions.

The skin often reflects internal processes. Some skin lesions are linked to cancers and may serve as "signposts" indicating the presence of a less visible internal cancer. Awareness of such skin changes can therefore result in earlier cancer diagnosis and treatment.

Skin lesions associated with cancers can be divided into two groups:

Skin diseases linked to internal cancer
Skin diseases due to the direct spread of internal cancers to the skin

These are often not cancerous in themselves and may disappear after the cancer has been surgically removed; and also reappear if the cancer recurs. Their presence should prompt your doctor to look for underlying cancers, although more often than not, cancer is not found.

Skin Manifestations of Internal Diseases

Acanthosis Nigricans (AN)

In this condition, the skin folds in areas such as the armpits, neck and groin appear thicker, dark and velvety. The nipples, navel, elbows and knees may also be affected. This skin disease may be associated with cancers in the gut and urine canal. AN often occurs simultaneously with the cancer and its course parallels that of the tumour. AN may be also be hereditary or associated with non-cancerous diseases, including diabetes mellitus, thyroid disease, hormone therapy, and obesity.

Blistering Skin Disorders

• Pemphigus, a group of skin disorders characterised by fragile blisters (Figure 2), may be associated with tumours of an internal gland called the thymus gland. Patients with this internal tumour often suffer from myasthenia gravis, a condition marked by an increased tendency for muscles to be fatigued and weak. Your doctor will perform examinations and X-rays to look for such tumours when necessary.

• Paraneo plastic pemphigus (Figure 3), another type of blistering skin disease, is marked by skin blisters and erosions with severe soreness and ulceration of the mouth and genitals. This skin disease is always associated with cancer of the cells of the lymph glands.

• Porphyria cutanea tarda (Figure 4) is a sunlight-sensitive skin disease, which appears as blisters and crusts on sun-exposed skin, usually on the hands, forearms and face. It is sometimes associated with increased facial hair and may occur in some patients with liver cancers.

Dermatomyositis

Patients with this skin disorder have sun-sensitive, purplish-red rashes on their eyelids, forehead, forearms and hands (Figure 5). The affected skin is often swollen. Weakness in the muscles is also common. This skin disease may occur in patients with an internal cancer. In Singapore, the most common associated cancer is nasopharyngeal carcinoma, a head and neck cancer.

Figure 5 Dermatomyositis

Arsenical Keratoses

This skin disease appears as corn-like hardening of the skin, resulting from chronic ingestion of arsenic (Figure 6). Arsenic may be found in some herbal medication which was previously used for the treatment of asthma. The skin lesions first develop on the palms and soles, and subsequently the trunk and limbs.

In time, each individual lesion may become cancerous. The skin disorder may be associated with cancers of the lung, throat and genito-urinary region.

Figure 6

Paget's Disease of the Nipple (EMP)

Paget's disease of the nipple appears as a red, crusted patch around the nipple (Figure 7). This skin disease, which may be mistaken for eczema, is often associated with breast cancer.

Figure 7

Exfoliative Erythroderma

The skin of patients with this condition is red and scaly over practically the entire body surface. There may be swelling of the skin, fever and debilitation. About 10 percent to 15 percent of such patients have an internal cancer, the most common of which is lymphoma (a cancer in the lymph nodes).

Peutz-Jegher's Syndrome

This condition is characterised by brown or black spots on the lips and inside the mouth (Figure 8). It is inherited, but up to 50 percent of patients do not have family members with the condition.

A small percentage of these patients have associated cancer of the gut, breasts or ovaries.

Figure 8

Neurofibromatosis

This condition is an inherited disorder. It is marked by multiple benign tumours (neurofibromas) on the skin. Two percent to five percent of patients with neurofibromatosis develop an internal cancer.

These patients may develop tumours in the brain (astrocytoma, glioblastomas) and adrenal glands (phaeochromocytomas). Patients with neurofibromatosis who develop headache, backache or hypertension should be investigated for internal cancers.

Skin Diseases Caused by Spread of Cancers to the Skin

Skin Metastases

Any internal cancer can spread to the skin. The development of skin lesions due to the spread of internal cancers is called "metastasis" (Figure 9). The tumours that most frequently give rise to skin metastases in Singapore include lung cancer, colorectal cancer and breast cancer. The presence of metastases in the skin usually indicates that the internal cancer has spread to other organs as well.

Figure 9

Sites of Skin Metastases

Certain sites appear to be favoured by particular tumours although it is not possible to generalise. For example, the scalp, face and neck are the most common sites of metastases from breast, lung and oral cavity cancers.

Metastases on the chest are most often from breast or lung cancer. The name "Sister Joseph's nodule" has been given to metastases on the navel from cancer in the abdomen, pelvis or breast.

Clinical Features of Skin Metastases

Metastases in the skin may appear as single or multiple nodules. The nodules are usually firm or hard, fixed or mobile. They often grow rapidly to one to three centimetres in diameter. The colour is variable and they may be red, brown, blue, black or flesh-coloured.

Management of Skin Metastases

When metastasis is suspected, a specimen of the lesion should be surgically removed (skin biopsy) to confirm the diagnosis. If cancerous metastasis is confirmed the patient should undergo investigation to determine the site of the internal cancers.

Treatment of the patient depends on the type of primary tumour, the degree of spread, and the overall physical condition of the patient. Medical options for therapy include radiotherapy and chemotherapy.

This article was last reviewed on Wednesday, November 22, 2023