The cause of a skin rash is usually a bacterial, viral or fungal infection. The probability that a rash is actually skin cancer is extremely low. A degeneration of a rash into a cancerous disease is impossible.
Although rashes do occasionally occur in the context of cancer, the skin change is then a concomitant phenomenon as an expression of the weakened defences of the entire organism, but not a cancer of the skin. Nevertheless, every skin rash should be presented to a doctor. This is advisable not least because the possible risk of infection for contact persons can be reduced by adequate treatment.
Although the doctor will give the all-clear in most cases, medicine is aware of a group of cancers that can indeed easily be mistaken for a skin rash. These are the so-called cutaneous T-cell lymphomas. The cutaneous T-cell lymphomas are characterized by an uncontrolled proliferation of a line of defense cells.
As the name T-cell lymphoma implies, the degeneration affects the T-lymphocytes, which are particularly common in the skin. The disease progresses insidiously and over many years, sometimes even decades. It is a malignant cancer that can affect the entire organism in later stages. The most common T-cell lymphoma is mycosis fungoides, which takes its name from the former confusion with a fungal disease of the skin (mycosis). Another T-cell lymphoma is the Sézary syndrome.
Mycosis fungoides is similar in its course to the other T-cell lymphomas. It progresses in three stages, the first of which, which resembles a skin eczema, can easily be confused with a common rash. Several round to oval, reddened foci of varying diameter develop, which in some cases form or moisten vesicles.
In the second stage, the pre-existing lesions increase in size and a plate-like, slightly raised pattern of the affected skin area is increasingly noticeable. It is not uncommon for severe itching to occur. The loss of hairs from the diseased skin is possible and there is occasionally swelling of the surrounding lymph nodes.
Only in the third stage, the so-called tumour stage, do tumour nodes develop, which impress as bulbous or lobed elevations of the skin. These tend to disintegrate and can form weeping ulcers. The Sézary syndrome begins with a general, highly pronounced reddening of the skin (erythroderma), which also becomes very scaly.
The diagnosis of cutaneous T-cell lymphoma is not easy and it often takes a long time before the final diagnosis is made. Especially in the early stages, the appearance resembles a normal skin rash. Lymphoma should be suspected if the course of a skin eczema is very long and resistant to therapy or if the findings are unusually persistent and resemble psoriasis.
If the usual therapies used for eczema or psoriasis do not lead to an improvement of the skin condition even after a long therapy period, a further examination of the disease should be carried out. The definitive diagnosis is made after the pathological findings of a skin biopsy. Itching is a common symptom of diseased skin.
It occurs frequently in bacterial, viral and fungal infections as well as in allergies and can have a lasting effect on the well-being of the affected patient. Although itching is a warning signal of diseased skin, as a symptom it is harmless in most cases. The unpleasant sensation provides indications of infection, dryness of the skin, excessive exposure to the sun or intolerance to certain foods or substances from the environment.
Almost every skin rash is accompanied by itching. Only in rare cases does chronic itching indicate cancer. In the case of the already described T-cell lymphoma, considerable, sometimes agonizing itching of the affected skin areas (mycosis fungoides) or of the entire skin (Sézary syndrome) can occur.
If severe itchy skin rashes or reddening of the skin persist over a long period of time despite intensive and adequate treatment, the initial diagnosis should be questioned and the cause of the disease investigated again. The birthmark, called nevus in medical terminology, is a benign proliferation of pigement-forming cells (melanocytes) of the skin. Each person has on average about 30-40 birthmarks of different size or colour.
Occasionally these can change their size, shape and appearance. Itching around a birthmark can also occur. Although the birthmark is a benign finding, degeneration can occasionally occur and skin cancer can develop.
This danger exists especially with very light skin types or with people with an unusually high number of birthmarks. A warning sign for the malignant degeneration of a birthmark is itching. However, this does not always mean that cancer is actually present.
As a precautionary measure, it is advisable to consult your family doctor or dermatologist, who will look at the birthmark from various angles. An assessment of the presence of skin cancer is made by the so-called ABCDE rule. Moles are considered suspicious if they show a pronounced asymmetry (A), are blurred (B), show several shades (F), have a large diameter (D, over 5mm) or if a rapid development (E) of the above-mentioned points can be determined.
The itching of a birthmark is therefore by no means a sign of cancer. Rather, several parameters must be considered and taken into account in the risk assessment. A bleeding birthmark should in any case give cause for a visit to the doctor.
In addition to itching, pain and weeping, bleeding from a birthmark can be a sign of malignant degeneration of the originally benign finding. However, as with itching, a bleeding birthmark does not necessarily mean cancer. On the contrary, the skin may have been injured by careless movement or may have become stuck to clothing because of its elevation.
The doctor will look at the suspicious birthmark under the aspects mentioned above and make an assessment. At this point it must be mentioned that according to recent studies the probability of a birthmark degenerating is only insignificantly higher compared to normal skin. In Western Europe about 10-15/100 000 people are diagnosed with black skin cancer every year.