Petechiae

Definition

Petechiae are small, pinhead-sized red spots on the skin or mucous membrane. They are caused by bleeding from small blood vessels (capillaries). If petechiae are present, they usually do not occur individually, but in a small or larger group of red dots.

There are various causes for the development of petechiae. Depending on the cause, they can be located in different places. Petechiae are not an independent disease but a symptom that can occur in the context of different diseases.

A typical feature of petechiae is that they do not disappear or fade even under pressure (for example, with a glass spatula). The therapy depends on the underlying disease. Finding a diagnosis is not always easy.

Causes of petechiae

There are different diseases where petechiae can occur. Often the appearance of these small punctiform bleedings indicates a disturbance of blood coagulation. In most cases a deficiency or a functional disorder of the blood platelets (thrombocytes) is the cause.

As a rule, petechiae develop first in the area of the ankles and lower legs. If more extensive petechial bleeding occurs in the context of thrombocytopenia, this is called thrombocytopenic purpura. Inflammation of the small blood vessels can also lead to small leaks in the capillaries and thus to blood leaking from them with the formation of petechiae.

This is then called vasculitis. The malfunctioning of the blood platelets can also be caused by taking medication. The so-called platelet aggregation inhibitors include acetylsalicylic acid (ASA) and clopidogrel.

An overdose can lead to the development of petechiae. In forensic medicine, petechiae play an important role for another reason: petechiae in the area of the head (for example, on the inner eyelids or on the mucous membrane of the mouth) can indicate strangulation before death, i.e., a non-natural death. Petechiae are caused either by an inflammatory reaction of the small blood vessels or by a deficiency or malfunction of the blood platelets.

Although stress generally increases the susceptibility of the body to disease, there is no known direct link in the development of petechiae. If petechiae occur without a recognisable cause and the doctor cannot identify a disease as the trigger, the cause often remains unclear. In addition to other explanations, it is then often suspected that stress may be partly responsible for the development.

However, there is no scientific proof of such a connection. A lack of blood platelets is known in medicine as thrombocytopenia. If the body no longer has enough platelets, primary haemostasis is impaired.

This can be shown by petechiae. A slight deficiency can only be detected in the blood but does not usually lead to symptoms or abnormalities. Only when the number of platelets is greatly reduced can spontaneous punctiform bleeding into the skin or oral mucosa occur, which can manifest itself as petechiae.

In the body, the blood flow constantly causes small injuries to the vessels, which can normally be sealed directly by the blood platelets. If there is a deficiency, this is no longer possible and petechiae develop without any apparent cause. Thrombocytopenia can have various causes, although inflammatory causes but also malignant diseases must be taken into account.

Vasculitis is an inflammation of the blood vessels and is one of the main causes of petechiae. There is an innumerable number of vasculitides, which can have different causes and can manifest themselves by different symptoms all over the body. Vasculitis should be considered when the number and function of the blood platelets is normal and there are other symptoms or laboratory changes that may indicate such a disease.

If vasculitis is suspected, special examinations are performed so that therapy can be initiated if necessary. If this is successful, the petechiae disappear again and no new ones appear. However, some forms of vasculitis cannot be cured, but their effects can be limited by medication.

Meningitis combined with the occurrence of petechiae is a very dangerous condition. Meningitis is an inflammatory disease of the meninges.It is triggered by pathogens such as bacteria or viruses and is typically accompanied by neck stiffness, fever and a significantly impaired general condition. Petechiae are not a typical symptom of “normal” meningitis.

Conversely, petechiae alone without further signs do not indicate meningitis as a cause. However, in a certain form of meningitis, namely that caused by meningococci (bacteria), the bacteria can be washed out into the bloodstream and thus lead to blood poisoning (sepsis). One speaks then of a meningococcal sepsis.

This blood poisoning can be accompanied by bleeding, i.e. large petechiae. The disease is very severe and acutely life-threatening and requires rapid intensive medical care. The various forms of leukemia (white blood cancer) can lead to a lack of platelets, especially in the acute forms.

This occurs because in acute leukemia the bone marrow is affected. Here, cancer cells multiply in large numbers, producing only white blood cells. Hence the name leukemia.

In healthy people, the bone marrow produces not only white blood cells but also red blood cells and platelets. In leukemia, however, the mass of cancer cells displaces the other, in itself healthy, cells and there is often a lack of red blood cells and platelets. The lack of blood platelets is called thrombocytopenia and often manifests itself in the form of petechiae.

These often appear first in the area of the ankle and lower leg. If petechiae occur in children and there is also, for example, an increased incidence of bruising, as well as increased fatigue and reduced performance, these can be signs of leukemia. A pediatrician should be consulted very promptly.

Petechiae have nothing to do with the liver. However, there are other small red skin symptoms that often occur in patients suffering from cirrhosis of the liver. These are called spidernaevi (vascular spiders).

There is a red spot in the middle that looks like a petechia on the outside. From this point small light red ramifications move outwards. A spidernaevi usually measures a few millimeters.

Such vascular spiders are mainly found in the area of the chest and face. If petechiae occur, a vitamin deficiency is a conceivable but very unlikely cause. In principle, a lack of vitamin C can lead to the punctiform skin bleeding, in addition to other symptoms of the bones and gums.

The clinical picture described as scurvy used to occur more frequently among sailors due to the one-sided and vitamin-poor diet. Nowadays a vitamin C deficiency is extremely rare. A deficiency of other vitamins is possible, but typically does not lead to petechiae.

A lack of vitamin K can also lead to bleeding, but this is more likely to result in flat rather than punctiform bleeding into the skin. In principle, strong pressure can lead to the development of petechiae. For example, high blood pressure in the blood vessels (especially in the skin capillaries) can be the trigger for spot bleeding.

However, this usually only occurs if there is a pre-existing reduction in the number of platelets or if their function is impaired. External pressure is unlikely to lead to petechiae. In the case of strong pressure, flat bleeding and thus bruising may occur.

In the field of forensic medicine, however, the development of petechiae through pressure is of particular importance. If a person is strangled to death, petechiae typically develop in the area of the eyes or the eyelids, so that it can be an indication of the cause of death. Petechiae can be triggered by a certain form of allergic reaction.

For example, the administration of some drugs or a blood transfusion can cause a reaction in the body that destroys platelets. If their proportion drops sharply, this can lead to spontaneous punctiform bleeding into the skin and mucous membranes and thus to petechiae. Common forms of allergies, such as those to food, grass or insect venoms, however, cause symptoms in a completely different way than the allergic reactions described above.

Petechiae are therefore not the consequence of such common forms of allergy. An infection with HIV can lead to various symptoms.Without treatment, AIDS usually breaks out a few years after the infection, which is characterized by a severe impairment of the body’s immune system. As a result, inflammatory reactions usually develop in various organs.

Among other things, petechiae can also develop in various ways. However, this is not a typical symptom of an infection with HIV. If there are no other symptoms besides petechiae, another cause for the punctiform bleeding is therefore much more likely.