Lichen Planus (cont.)

Lichen planus can be distinguished from eczema, psoriasis, and other common rashes purely on the basis of its clinical appearance in that lesions are small bumps or aggregations of bumps that are flat-topped, shiny, polygonal, purple to grey in color, tend to occur at the wrists and elbows and ankles, and on close examination contain thin white lines called Wickham's striae. When lichen planus involves the oral tissues, such as the lips or cheeks, these white filmy lines are easy to detect. It is not unusual for lichen planus to appear at sites of trauma, especially along lines of scratches (excoriations).

Lichen planus itches with an intensity that varies in different people from mild to severe.

The onset of lichen planus can be sudden or gradual. The first attack may last for weeks or months, and recurrences may happen for years. The bumps at first are 2 mm to 4 mm in diameter, with angular borders and a violet color. An excess of pigment (hyperpigmentation) may develop in the affected skin as the lesions persist. Rarely, a patchy, scarring balding (alopecia) of the scalp occurs.

The appearance of lichen planus depends on whether the skin or the lining (mucous membranes) inside the mouth or vagina are affected:

• Skin involvement: The usual skin involvement with lichen planus consists of flat-topped lilac or violet spots a few millimeters in diameter on the skin. These spots tend to be located on the inner wrists, forearms, the lower legs just above the ankles, and the lower part of the back.
  
  A variant of this disease is called hypertrophic lichen planus. This condition appears as thick, reddish-brown lesions that are covered with scales. These spots tend to be on the shins, but they can occur anywhere on the body. This is an especially itchy and persistent (chronic) variant of lichen planus.

• Mucous membranes: Lichen planus of the mucous membranes is common. Dentists often come across it as a white, lacy rash on the inside of the cheeks of people who are unaware of the condition. About half of the people affected with lichen planus have the rash inside of their mouths (oral mucosa). The oral rash often occurs prior to any skin involvement.
  
  More troublesome, although rare, is erosive lichen planus, which can be quite sore and uncomfortable. This erosive form typically causes the patient to complain of the shallow and often quite painful, recurrent ulcers in the mouth.
  
  Lichen planus can affect the female genitals, including the vagina. This condition can be confused with sexually transmitted diseases (STDs), although lichen planus is neither sexually transmitted nor contagious.

Sometimes, lichen planus produces pits and grooves in the nails as well.

Source: MedicineNet.com
http://www.medicinenet.com/lichen_planus/article.htm