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 may thus result in earlier diagnosis and treatment of cancers. These skin lesions associated with cancers can be divided into 2 groups:
- Skin diseases linked to internal cancer.
- Skin diseases due to the direct spread of internal cancers to the skin.
These skin diseases are often not intrinsically cancerous but may occur in individuals with internal cancers. Some of them occur at the same time as the cancers. Some of these skin diseases disappear after the cancer has been surgically removed and reappear when the cancer recurs. The presence of these skin diseases should prompt your doctor to look for underlying cancers. More often than not, no cancer are found to be present.
a. Acanthosis Nigricans (AN)
In this condition, the skin folds in areas such as the armpits, the neck and the groins appear thickened, 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 hereditary or associated with noncancerous diseases including diabetes mellitus, thyroid disease, hormone therapy and obesity.
b. Blistering Skin Disorders Fig.2
Fig.2 Blistering Skin Disorders
Fig.3 Paraneo-plastic pemphigus.
Fig.4 porphyria cutanea tarda
Pemphigus, a group of skin disorders characterised by fragile blisters, may be associated with tumours of any 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 fatigue and weak. Your doctor will perform careful examinations and X'rays to look for such internal tumours when necessary.
In another type of blistering skin diseases called paraneo plastic pemphigus Fig.3 , the 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 a cancer of the cells of lymph glands.
A sunlight sensitive skin disease called porphyria cutanea tarda Fig.4 which presents with blisters and crusts over the sun-exposed skin, usually the hands, forearms and face, and sometimes associated with increased facial hair may occur in some patients with liver cancers.
Patients with this skin disorder have sun-sensitive, purplish-red rashes on their eyelids, forehead, forearms and hands. Swelling of the
affected skin is common. Muscle weakness often occurs. This skin disease may occur in patients with an internal cancer.
In Singapore the commonest associated cancer is nasopharyngeal carcinoma.
DEDICATED TO EXCELLENCE IN DERMATOLOGY
By National Skin Centre (Singapore)
Copyright (C) 1995 - National Skin Centre (Singapore)