Reasons for purple spots on the skin

Many people will inadvertently find that they have purple spots on their bodies, and they still don’t know where they come from after thinking for a long time. This is because some people have high capillary fragility and are prone to bruises. When small blood vessels are damaged, a small amount of blood will overflow, leaving small red dots and purple spots on the skin. Of course, this is only one of the situations. Today I will tell you the reasons for purple spots on the skin. Let’s learn about it together.

Causes of ecchymosis:

(1) Extravascular factors. If the tissues surrounding the blood vessels become weak due to degeneration, atrophy and relaxation, bleeding is likely to occur and purpura may form. Extravascular factors are more common in senile or cachectic purpura. Capillaries and small blood vessels can be ruptured and bleed by slight external force, leading to purpura.

(2) Vascular factors. It refers to purpura caused by damage to the capillary walls, which causes blood to leak out of the blood vessels. Purpura caused by vascular factors accounts for the first place among all purpura. When small blood vessels in a normal person are injured, the blood vessels immediately undergo reflex contraction and local blood flow slows down to promote hemostasis. If the peripheral blood vessels are fragile, permeable and vasomotor function is abnormal, hemorrhagic purpura may easily occur due to blood infiltration into and out of the blood vessels. The characteristic of bleeding caused by vascular factors is that the capillary fragility test is positive, but the bleeding time and clotting time are normal. The most common type of purpura is allergic purpura. Secondly, bacterial or viral infection, vitamin C deficiency, chemical factors, etc. can damage the blood vessel walls and cause purpura. In addition, there is a type of increased fragility of the blood vessel walls for unknown reasons, which is common in women. Purpura may disappear on its own without any adverse consequences. This is called simple purpura.

(3) Platelet factors. Platelets play an important role in the hemostasis process. Thrombocytopenia or platelet function deficiency will weaken or lose the hemostatic function, which can easily lead to purpura. Thrombocytopenia can be seen in idiopathic thrombocytopenia, secondary thrombocytopenia (also known as symptomatic purpura, which can be caused by bone marrow hematopoietic disorders leading to a decrease in platelets, seen in aplastic anemia, leukemia, and bone metastasis of cancer), radioactive substances and chemicals destroying megakaryocytes and reducing platelet production, severe infections (such as typhoid fever, meningitis, sepsis) causing excessive platelet destruction, etc. In addition, hypersplenism, lupus erythematosus, uremia, etc. can also cause thrombocytopenia. Platelet function deficiency diseases include hemorrhagic thrombocythemia, thrombasthenia, etc. Laboratory tests are of great significance for the diagnosis of purpura caused by platelet factors, which generally manifests as prolonged bleeding time, poor clot retraction and thrombocytopenia.

(4) Coagulation factor factors. Coagulation factor deficiency often leads to coagulation disorders and causes purpura. This type of disease is rare, and the causes are mostly congenital, with a few being acquired (mainly caused by liver disease). Purpura patients should undergo blood routine examination, platelet count, bleeding time, coagulation time, capillary fragility test, skin and mucous membrane microcirculation, blood rheology and coagulation factors and other related examinations.