Formation of Plaques

Psoriasis is a genetically determined disposition of the skin to chronic inflammation characterised by an increased epithelium production, which appears as a response to certain external or internal impacts. On the affected area the skin becomes 6 times thicker than its normal diameter. The new epidermis forms itself 10 times faster than it does in healthy skin. Psoriatic plaques are caused by abnormally accelerated proliferation of skin cells. Generally one or more small plaques appear, at first on the scalp, elbows, knees, back, or nates. The first plaques can spontaneously subside after a few months, but they can also remain; in the latter case, they unite into larger plaques. A plaque is a several centimeters large, red deformation on the skin surface, characterised by white exfoliation. The name of the disease itself also derives from exfoliation. The Greek word „psora” means „a scale”.


Predisposition to Psoriasis and Environmental Impacts

Note: it is only the susceptibility (disposition) to the disease that is hereditary, but not the disease itself. Genetic predisposition is not enough to evoke psoriasis; the disease doesn’t appear without the impact of external, environmental provoking factors that bring forth the innate susceptibility. Provocation means in this case that if someone has a hereditary, genetic predisposition to psoriasis, some „stimuli” will trigger psoriatic symptoms on his or her skin. Such are mechanical impacts on the skin, especially injuries (burns, insect bites, tattoos, operations), mycotic or bacterial skin infections, or other skin inflammations (e.g. allergic eczema, viral infections). An internal disease can also be one of these „external” impacts, just like any other influence that is able to make psoriasis appear on the skin of a patient susceptible to the disease. Psoriatic skin symptoms develop when the combined influence of predisposition and provoking factors reaches the liminal value that makes it possible for the disease to appear.


„Internal Provoking Factors” of Psoriasis

„Internal“ provoking factors affecting the whole body are diabetes, liver diseases, tumours of internal organs, and also latent, chronic inflammatory focuses that cause no acute symptoms, such as chronic tonsillitis, ovary inflammation or prostatitis, abscesses and inflammations of the gums, or chronic sinusitis. The appearance of psoriasis often calls attention to some hitherto unnoticed, hidden disease.
Some medicines can also evoke psoriasis. The most important of these are the so-called beta blockers, frequently used as antihypertensives, and lithium administered in psychiatry. Non-steroidal anti-inflammatory drugs that are nowadays sold without prescription, or rarely used synthetic anti-malaria drugs can also make the symptoms worse. It must not be forgotten that alcohol consumption has also been proved to be of provoking effect. In addition, the influence of stress is also important, since the appearance of the symptoms is often triggered by psychological factors. Beyond these, many theories have been raised in order to explain the exact reasons for the development of this skin disease. By now the stages of the immunological inflammatory process appearing in the skin symptoms have been surveyed very thoroughly.


Psoriatic Skin Symptoms

Psoriasis can appear in a variety of forms. A nearly always observable, so-called primary phenomenon of it is a dark red, exfoliating elevation of the skin surface (papule). Papules can be 1–2 centimeters in diameter (psoriasis guttata), but characteristically they unite into so-called plaques of several centimeters. Plaques separate themselves from healthy skin surface in a well-defined way. Their surface is covered by scaly, waxy-white exfoliation (parakeratosis). This exfoliating layer is easy to scrub away. After scrubbing a tiny, punctate bleeding appears, the so-called Auspitz’s sign, showing that the skin’s blood vessel system also undergoes an abnormal change in psoriatic plaques. Another characteristic of the disease is the so-called Koebner phenomenon, that is, the appearance of psoriatic papules as a response to various kind of stimuli on the skin (e.g. in operation scars or around piercings) after about two weeks.


Appearance on Various Body Parts

Psoriasis develops typically on e. g. elbows and knees, for these are more liable to injuries like hitting or scratching. It is also frequent on hairy scalp in the form of bulky exfoliation. On the nails small, pinprick-like dots can appear. Psoriatic symptoms are painless, generally not even itchy. However, in 5% of the cases the disease attacks the joints as well (arthropathia psoriatica). Articular pain can be noticed even before the appearance of skin symptoms. It can affect not only small joints in hands and feet or vertebral joints, but larger joints as well, such as those of hips, knees, ankles, or shoulders. Later on, these articular inflammations can lead to deformities.

Luckily it is rare that psoriatic symptoms affect the whole of the continuous skin surface (erythroderma psoriaticum). In such cases the whole skin surface is inflamed, red, exfoliating, and swollen lymph nodes appear, too. It can be accompanied by complete hair loss. This form of psoriasis necessitates hospital treatment.

In the most severe form of the disease pustules appear on the skin. These small pus bladders can be only 1-2 mm large or even several centimeters in diameter. In milder cases they appear only on the palms of hands and soles of feet, but in more dangerous cases they affect the whole body. This can be accompanied by severe enterological complications, infections, even sepsis can develop.