The ageing of the tegument is an irreversible biological phenomenon common to all animals. Cutaneous ageing is complex, and results from the sum of an intrinsic process and of environmental aggressions, of which solar radiation most stands out. In short one might say that cutaneous ageing depends on the intrinsic mechanism, on external factors and on alterations to other organs. Resulting from this triad of influences are structural, biochemical and functional modifications that affect the epidermis, dermis and annexes.

Some of the alterations to the cutaneous tegument of older people are easy to detect: the skin, mainly in the exposed areas, becomes atrophic, loses its normal elasticity and forms wrinkles. Old skin is dry, rough and transparent. The intensity of these characteristics varies from one individual to another. The phototype is important, as well as the lifestyle, one’s profession or occupations. In analyzing the clinical translation of cutaneous ageing solar radiation stands out as an external factor, as we can see when observing the aged face of an agricultural worker compared to that of an office worker.

In most individuals solar radiation is responsible for most of the cutaneous alterations that characterize ageing, as well as for the distribution of these alterations, which can be observed in areas usually exposed to the sun and not in areas that are not exposed.

Figure 1 – Cutaneous Ageing and Photo-ageing
These are more noticeable in Caucasians, with fair skin, living in areas of the planet in which the quantity of solar radiation received annually is greater than in their countries of origin. Macroscopic alterations in the skin, mainly underlying which is actinic degeneration, consist of: forming of wrinkles in a varying quantity with the anatomical region, yellowed discolouring, loss of elasticity and the dilating of the surface blood vessels, particularly on the face. On the back of the hands one can see anomalies in the pigmentation, and there are many other alterations such as telangiectasias, star-shaped scars, giant warts and freckles. In cutis romboidalis, which is observed in individuals whose profession was or is fishing or agriculture, the skin on the back of the neck becomes thick with deep grooves, as if drawing out a mesh of diamond shapes.

The structural alterations to the epidermis that accompany the ageing process are dominated by the reduction in thickness, essentially to the cost of the mucous body, and a decrease in adhesion among the keratinocytes. In the areas of exposed skin there is normally an increase in mitoses in the supra-papillary areas according to age and exposure to the sun. There appears to be a reduction in the number of metabolically active melanocytes with age. On the skin exposed to solar radiation the number and functional activity of Langerhans cells are reduced.

Rectification of the dermo-epidermic junction is one of the main characteristics of ageing skin, and is the most typical and consistent phenomenon of ageing skin. There is a rectification of the junction between the two tissues and a reduction in height, or even the disappearing of the dermic papillae and the inter-papillary epidermal ridges.

The harmful effects of solar radiation on skin are accumulative, which leads to the relative irreversibility of the alterations that have taken place and accentuate those of innate ageing. Solar radiation seems to exacerbate the decrease in epidermal thickness and the disappearing of epidermal ridges and to condition the increase in pigmentation in certain areas. In photo-aged skin discolouring alterations may be one of the most obvious clinical characteristics.

The modifications seen on the dermis during the ageing process are among the most relevant ones, with particular note, in relation to the non-exposed skin, for a reduction in the thickness of the dermis with cell rarefaction both in fibroblasts and in mastocytes. In the exposed skin, at an early stage, one can see an increase in the number of mastocytes and a decrease in the number of fibroblasts, with some being hyperplasic.

The alterations of the extra-cellular matrix of the dermis affect the collagen, the elastin and the glycosaminoglycans. When penetrating to the reticular dermis, UVA stimulate the fibroblasts to produce an excess of abnormal elastic fibres. In photo-ageing what stands out on the dermis is the actinic elastosis that is characterised by a marked modification of the fibres in the elastic system. Actinic elastosis is most noticeable in phototypes I and II, and is correlated to accumulative doses of received solar radiation. Besides the fibrous support proteins, the glycosaminoglycans, on the extra-cellular matrix of the dermis, also undergo important alterations during ageing, both on skin exposed to and not exposed to solar radiation. The biochemical studies carried out in our laboratory show that over the ageing period on skin there is a reduction in the total content of glycosaminoglycans, in particular in relation to dermatane sulphate.

Of particular note among the epithelial neoplasias are basalioma and espino-cellular carcinoma. Basalioma is characterised by a slow evolution without metastization. Its possible malign nature has to do with its local invasive capacity. It is very frequent in white people, and rare in black people. It occurs most frequently after the age of fifty, particularly in areas exposed to sunlight. It is not seen in the mucous areas or on the palms of the hands or soles of the feet. It starts out as a small, hard transparent hemispherical pimple. In months or years the evolution of the tumour progresses, with accentuated polymorphism.

The espino-cellular carcinoma appears on actinic keratosis in about 50% of cases. The lesion increases in size and becomes procident. The espino-cellular carcinoma is most often to be found in the uncovered areas than the covered ones. Clinical evolution is quicker than basalioma, with nodular or ulcero-vegetant morphology. The invasive nature is variable in its speed and intensity. Espino-cellular carcinomas located in the genital organs, the auricular pavilions and on the lips have a bad prognosis.

Malign melanoma is a tumour that deserves special attention due to its seriousness.

Figure 2 – Malign Melanoma

Incidence of this cutaneous neoplasia has progressively increased, particularly in the white race with low pigment capacity. It has been seen that in the same geographical area the incidence of malign Melanoma in the population with the Mediterranean cutaneous sub-type is about six times less than in Caucasian individuals with fairer skin. There is a very low rate of occurrence in the black race.

In the main treatises on dermatology one may read that it is UV radiation lesion, particularly in childhood, sunburn that affect the melanocytes more than chronic exposure to the sun, that is involved in the pathogeny of melanoma.

Incidence of cutaneous melanoma has had a significant increase over the last fifty years, and today is ten times higher than forty years ago and still growing more rapidly than any other malign tumour. Malign melanoma in the USA went from twentieth place as a cause of cancer in 1985 to eighth place over recent years. The lifetime risk for melanoma in the USA is 1/80, and is even more prominent for individuals of Celtic origin with red hair. In some regions of the USA and of Australia the lifetime risk is 1:25. In white Europeans the lifetime risk for melanoma has increased drastically from 1:1500 in 1935 to 1:75 in 2000, which represents a doubling of occurrence each decade.

Melanoma should be a preventable tumour as it develops in full sight of the patient, the family and the doctor. Primary prevention with sun protection and early excision as secondary prevention are of vital importance. I would risk suggesting an exam of oneself every three months and observation by a dermatologist every six months for individuals with lower phototypes.

Two stages are essential for early detecting of malign melanoma: a) the patients must learn to identify suspect melanocytic marks and rapidly see a dermatologist for assessment and therapeutic treatment; b) all doctors should be taught to appreciate the morphology of each early malign melanoma so that at each visit to the doctor a screening is carried out. For early diagnosis it is vital for each doctor to know what an initial melanoma looks like and how to rapidly send the patient to a dermatologist.

One achieves 80% of solar exposure at the age of 18. Over 90% of all skin cancers take place in body areas exposed to the sun. There is no unequivocal evidence that the use of sun protectors may diminish or invert the incidence of melanoma. Application of sun protectors as an isolated measure is insufficient and potentially dangerous, and should be used as a part of a set of measures in which they take a secondary position. External photoprotection includes attitudes that go from the choice of clothing to that of one’s profession, going through leisure activities, outdoor activity times, holidays, sport, etc… in textiles it is also possible to determine the levels of protection, normally expressed in UPFs (Ultraviolet Protection Factor), and, like cosmetics, this index measures the effective protection afforded by the textile.

Photoeducation has the aim of promoting behaviour patterns that will avoid the harmful effects of over-exposure or inadequate exposure to ultraviolet rays: to stimulate solar exposure only to adequate times, to avoid sunburn or prolonged exposure, to use not only a sun protector but above all suitable clothing and other methods of sun protection.

The Associação Portuguesa de Cancro Cutâneo (Portuguese Skin Cancer Association), with the sponsorship of the Portuguese Dermatology Society, Portuguese League against cancer and the General Directorate of Health have carried out awareness raising actions for the population, particularly younger people.

João Pedro Freitas
Graduate Hospital Assistant at Santa Maria Hospital, Dermatology Assistant at the FMUL
joao_pedro_freitas@hotmail.com

References
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