A small red spot suddenly appears on the back of the hand. It doesn't hurt or itch. Pressing it will disappear and then appear again (what does pressing fade mean? Does this belong to pressing fade?) It has also appeared before. I used to soak my hands in warm water or blow the heater for a while. (the actual color is a little darker than that in the figure)
There are small red spots on the back of the hand, which will disappear after pressing, indicating that it is not subcutaneous bleeding, because if it is bleeding, the pressing will not disappear, indicating that it is a rash, which may be the manifestation of allergy caused by contacting something. If it is not painful or itchy, I think it does not need to be treated, and it may disappear after a period of time
For this situation on the arm, we should combine some local drugs to improve the symptoms of the disease. At ordinary times, we should pay attention not to eat some irritating food as much as possible, which will be affected to some extent. You can apply it locally with vitamin A or desnide cream.
According to the picture, there is no big problem. It may be due to allergies caused by cold air. As you said, using warm water or heating period will disappear. It is suggested to keep warm when you go out.