Unusually pale.
Pale skin can be caused by anemia, peripheral capillary spasm or insufficient filling, such as cold, panic, shock, collapse and aortic valve insufficiency. Only the limbs are pale, which may be related to limb arterial spasm or obstruction, such as Raynaud's disease and thromboangiitis obliterans.
Abnormal face 2- redness
The redness of the skin is caused by telangiectasia and congestion, accelerated blood flow, increased blood volume and increased red blood cells, which can be seen after exercise and drinking under physiological conditions. Pathological conditions are found in febrile diseases, such as streptococcus pneumoniae pneumonia, tuberculosis, scarlet fever, atropine and carbon monoxide poisoning.
Abnormal cyanosis of face
The skin is bluish purple, which often appears on lips, auricles, cheeks and limbs. It is seen in the increase and decrease of hemoglobin or abnormal hemoglobinemia.
Abnormal face with four yellow stains
The so-called yellow dyeing is what we see when the skin turns yellow. There are usually several reasons. First, jaundice is generally caused by hepatobiliary diseases. Second, the increase of carotene: excessive consumption of carrots, pumpkins, oranges, orange juice and so on. It can cause the increase of carotene in the blood, which will make the skin yellow when it reaches a certain amount. In addition, if you eat drugs containing yellow pigment for a long time, yellow dyeing will also occur.
Abnormal face is the easiest to find in life, and there are many abnormal faces, so I won't list them here. You are welcome to add other things that are not mentioned in the comment area.