Macule and Patch

• Macules and patches are characterized by an area of the skin that has changed color. If it is no more than 1 cm in diameter, it is considered a macule. If it is greater than 1 cm, it is considered a patch.
  
  

Papules and Plaques

• A papule is a raised portion of the skin that is solid and less than 1 cm in diameter. A plaque is larger and has a flat top. It is formed when papules are grouped together. A purpura is a type of papule that is formed when there is bleeding in the skin, and it is characterized by a reddish color.
  
  

Nodule

• A nodule is similar to a papule except that it is greater than 1 cm in diameter and usually grows deeper into the skin.
  
  

Tumors and Cysts

• A tumor is an abnormal enlargement of tissue that may involve any part of the skin as well as the underlying tissue. A cyst is often confused with a tumor, but it is a cavity that can contain fluid or solid material. It is smooth to the touch, and can be either compressible or solid depending on what it contains.
  
  

Pustules and Abscesses

• A pustule is a small, raised lesion that is filled with pus. It is usually found between the layers of skin or in the hair follicles. An abscess also has pus in it. It is a soft, compressible lesion that forms as a result of pus accumulating just below the skin.
  
  

Wheals and Angioedemas

• A wheal is a raised lesion with a flat top. It consists of edema, which is an unusual collection of water in the body, that quickly appears and disappears within a matter of minutes or hours. An angioedema is similar to a wheal except that the edema is deeper in the skin, which results in more diffuse swelling.
  
  

Vesicles and Bullas

• A vesicle is a raised lesion that is filled with clear liquid that is smaller than 1 cm in diameter. This is commonly referred to as a blister. If it is greater than 1 cm in diameter, it is referred to as a bulla.