skin lesions

In medicine, the term lesion refers to any abnormality of tissue in the body.

The Primary Lesions

[wonderful site about skin nomenclature & pictures]

Primary lesions are physical changes in the skin considered to be caused directly by the disease process. Types of primary lesions are rarely specific to a single disease entity.

macule:

A macule is a change in the color of the skin. It is flat, if you were to close your eyes and run your fingers over the surface of a purely macular lesion, you could not detect it. A macule greater than 5mm may be referred to as a patch

The color of the lesion is one way in which a diagnosis may be focused.

Macules by color :

• 
  Brown
  Becker's nevus
  Café-au-lait spot
  Freckle
  Melasma
  Photoxic drug eruption
• 
  Blue
  Ink (tattoo)
  Mongolian spot
  Ochronosis
• 
  Red
  Drug eruptions
  Juvenile rheumatoid arthritis
  Rheumatic fever
  Viral exanthems
• 
  Hypopigmented
  Piebaldism
  Radiation dermatitis
  Vitiligo
  Tuberous sclerosis

PAPULE

A papule is a solid raised lesion that has distinct borders and is less than 5mm in diameter. Papules may have a variety of shapes in profile (domed, flat-topped, umbilicated) and may be associated with secondary features such as crusts or scales.

An id reaction is a generalized hypersensitivity reaction on the skin to a local inflammatory lesion of the skin (e.g., a fungal infection).

note:

• The papules of psoriasis are flat-topped and red, often with a superimposed scale that produces bleeding when removed.
• Skin lesions of a secondary syphilis are copper colored.
• Violet papules are typical of lichen planus skin lesions,
• the papules of lichen sclerosis are whitish.
• Rounded, red, bluish-red, or brownish-red papules characterize the skin disease pyogenicum.

NODULE

A nodule is a raised solid lesion more than 5mm but less than 2 cm.and may be in the epidermis, dermis, or subcutaneous tissue.

Examples of nodules include:

• keratinous cysts,
• small lipomas (benign tumors composed
  of mature fat cells),
• fibromas (benign tumors derived from fibrous connective tissue),
• some types of lymphoma (malignant diseases usually in the lymph nodes),
• variety of neoplasms (abnormal, excessive, and uncontrolled multiplication of cells forming a mass or new growth of tissue)

Tumor.

A tumor is an elevated, solid lesion greater than 2 cm. Tumor, a
general term for any mass, benign or malignant, is sometimes used to indicate a large nodule.

PLAQUE

A plaque is a solid, raised, flat-topped lesion greater than 5mm. in diameter. It is analogous to the geological formation, the plateau

VESICLE

Vesicles are raised lesions less than 5mm. in diameter that are filled with clear fluid.

BULLAE

Bullae are circumscribed fluid-filled lesions that are greater than 5mm. in diameter.

Blisters are classified as vesicles if they are 0.5 cm (0.2 inch) or less in diameter and as bullae if they are larger.

PUSTULE

Pustules are circumscribed elevated lesions that contain pus. They are most commonly infected (as in folliculitis) but may be sterile (as in pustular psoriasis).

WHEAL

A wheal is an area of edema in the upper epidermis.

Twenty-five percent of the normal population can produce wheals
merely by stroking their skin. This phenomenon is called dermatographism.

Dermatographism means the ability to write on the skin. People with this form of chronic urticaria are sensitive to touch and pressure, as well as scratching. The areas of skin that are touched or scratched get a raised, red and itchy rash. While many people with chronic urticaria have some features of dermatographism, people with true dermatographism have pressure as the only trigger for their symptoms.

so now in brief the above lesions:

discolored area at level of skin:if less than 5mm-macule

if more than 5mm-patch

solid raised lesion:if less than 5mm-papule

if more than 5mm to 2cm& round-nodule

if more than 2cm-tumor

if more than 5mm & flat topped-plaque

raised lesion filled with fluid:if less than 5mm-vesicle

if more then 5mm -bullae

if it is pus filled{irrespective of size}-pustule

next post will be on secondary skin lesions & special lesions.