Cyanosis

• Blue-tinged feet may mean that you are suffering from cyanosis, according to the National Institutes of Health. The mucus membranes or skin can turn blue due to lack of oxygen in the blood. The blue tint can also appear on your nose, ears, lips, gums, around your eyes and in your nail beds, and is more apparent in dark-skinned people.
  
  

Raynaud's

• A condition called Raynaud's phenomenon can cause your feet to turn whitish blue. If you have this condition, cold temperatures or even strong emotions can cause your blood vessels to spasm, which blocks the blood flow to your feet, toes, ears, nose and fingers.
  
  

Other Medical Conditions

• Additional medical conditions that can lead to discolored feet and other body parts include pulmonary hypertension; hyaline membrane disease, which can occur when an infant is born prematurely; pneumonia; bronchiolitis; and COPD or chronic obstructive pulmonary disease. A blood clot in your lung arteries, which is called a pulmonary embolism, can also result in discolored skin.
  
  

Frostbite

• If your feet are frostbitten, they will become discolored.
  
  

Ulcers

• The Cleveland Clinic notes that ulcers can cause skin discoloration as well as a rash, redness, burning and itching.