Lichen Planus

Lichen planus is an uncommon condition which typically affects the skin and/or mucous membranes. It commonly affects a smaller area, but some affected persons may see substantial surface coverage. Lichen planus comes in different forms which appear in different areas.

Classical lichen planus consists of firm papules which are flat and shiny and may form closed together or be widespread. These lesions may vary from very tiny to over 1 cm, and are purple in color and often crossed by small white lines. Classical lichen planus will typically appear in straight lines or circles, which usually form on the wrists, ankles or lower back, though lesions may form on any part of the body. Lesions may be accompanied by severe itching, especially those around the ankles, and after clearing may leave areas of hyperpigmentation, grayish-brown, which may take months to resolve.

Other major types of lichen planus include oral lichen planus (typically affecting the cheeks, sides of the tongue, gums, and lips with a white fern pattern or streaks, accompanied by painful mouth ulcers and redness and peeling of the gums), vaginal lichen planus (peeling of surface cells in the vagina causing discharge and possible bleeding), Erosive lichen planus (affects the vagina, causing pain and red, raw mucosa, and may scar. May also affect the eyelids, ear canal, esophagus, larynx, anus, and bladder.), penile Lichen planus (papules around the tip of the penis), Lichen planopilaris (spiny red papules surrounding follicle clusters, which may lead to permanent hair loss), Lichen planus of the nails (nails become ridged, darken in color, and thicken or lift from the nail bed, may also be accompanied by destruction and scarring of the cuticle, nail shedding, loss of nails and/or nail growth) Lichen planus pigmentosa (brownish grey oval lesions form on the neck and face or limbs and torso), actinic lichen planus (forms in sun exposed areas), and bullous lichen planus (rare, blistering form, appears on the lower legs). In lichenoid drug eruptions, characteristic lesions form due to a reaction to certain medications, such as gold, antimalarials, captopril, quinine, and thiazide based diuretics.

While the exact cause is unknown, it is thought that lichen planus is the result of a faulty immune system response in which the skin is attacked, and is typically due to viral infection or drug reaction. It usually clears within 18 months, but may last longer depending on the location and severity of the condition. In rare cases, longterm erosive lichen planus may increase the risk of skin, vulvar or penile cancer.

Differential Diagnosis (Other conditions with similar appearance)
Graft versus host disease
Psoriasis, Guttate
Lichen Nitidus
Psoriasis, Plaque
Lichen Simplex Chronicus
Syphilis
Pityriasis rosea
Tinea Corporis

Lichen planus is typically diagnosed based the characteristic appearance of the affected area. A skin biopsy may be performed to confirm the diagnosis and to rule out other conditions or complications.