What is the reason for the appearance of blue spots on the body without being hit?

What is the ;a reason  The appearance of blue spots on the body without being hit?
A decrease in the proportion of platelets in the body by less than two thousand platelets, and this leads to the appearance of blue spots on the body without any blow or bruising on it. . . .
Taking some types of medications, such as blood thinners or anticoagulants, such as aspirin or non-steroidal anti-inflammatory drugs, can inhibit the normal function of platelet work, in addition to other types of medications that thin the skin and cause internal bleeding from under it. Like cortisone. . .
Having blood-related diseases, or having problems in the blood clotting process. . Cirrhosis or cirrhosis of the liver as a result of hepatitis C infection or alcohol-related liver disease.
* A state of strong psychological trauma, as some recent studies have proven that there are some people who suffer from the appearance of blue spots in different areas of their body after exposure to severe trauma. . .
* Lack of collagen in the body, especially after aging, where human skin becomes more thin and soft, which leads to bleeding under the skin easily and with less movement.
There is a deficiency in some types of vitamins in the body, as vitamin C is one of the most important vitamins whose deficiency leads to the appearance of pigmentation or blue spots on the body.
* Permanent and direct exposure to the sun's harmful rays without protection.