Lichen planus causes a characteristic rash that can occur alone or as a feature of other autoimmune disorders and syndromes.
Lichen planus is an autoimmune dermatological condition that can occur as a primary condition or as an accompanying feature in other autoimmune conditions. It is also reported to occur in hepatitis B and hepatitis C infections. Overall, lichen planus is seen in about 0.5 percent of the population. It affects people of all ages, but men tend to be affected at a younger age than women.
Lichen planus is associated with the following autoimmune conditions: alopecia areata, vitiligo, dermatitis herpetiformis, pemphigus, scleroderma, primary biliary cirrhosis, autoimmune hepatitis, ulcerative colitis, thyroiditis, systemic lupus erythematosus (SLE), diabetes mellitus, and pernicious anemia. Lichen planus also frequently occurs with systemic lupus erythematosus as an overlap syndrome. Cases of lichen planus/lupus erythematosus overlap syndrome have also been reported to occur in association with a scarring form of alopecia.
Lichen planus is also reported to occur as part of Multiple Autoimmune Syndrome associated with Reynolds-syndrome. Reynolds syndrome is characterized by acral scleroderma, primary biliary cirrhosis, and Sjogren’s syndrome. In Multiple Autoimmune Syndrome, Reynold’s syndrome is associated with lupus erythematosus/lichen planus overlap syndrome.
The specific cause of lichen planus is not known, but it may be a hypersensitivity reaction by the immune system to a variety of drugs (especially gold salts, bismuth, arsenic, quinine, quinidine, and quinacrine) and various chemicals (including certain chemicals used to develop color photographs), and infectious organisms.
Symptoms
Lichen planus causes small lesions, which may be ulcerative or erosive, that are violet or purple, with multiple angles occurring as flat-topped papules or small plaques. Usually, these lesions are extremely itchy although in some cases they don’t itch. Scratched lesions, which are commonly seen in eczema, are rarely seen in lichen planus. However, the surface of lesions typically has a white lace-like pattern known as Whickham’s striae, which is enhanced when mineral oil is applied to the surface of the lesion.
The lesions in lichen planus tend to cluster together and frequently overlap. Lesions are most often seen on the wrists, forearms, shins, heels, and ankles. New lesions continue to appear for a few weeks to several months. Untreated, the eruptions of lichen planus usually persists for about 12-18 months. In palmoplantar lichen planus, the palms of the hands and soles of the feet are primarily affected.
Lichen planus is one of several disorders that exhibit the Koebner reaction. In this reaction, new lesions develop at the sites of minor injuries, such as scratches or burns within a week of the injury, suggesting the development of lesions is an abnormal manifestation of the normal inflammatory response.
Older lesions, which are starting to heal, and sometimes new lesions as well, may occasionally develop a muddy-brown pigmentation, which may be intense in skin creases.
In about 75 percent of cases, patients with lichen planus develop oral lesions with a white lace-like pattern.
Diagnosis
Lichen planus must be differentiated from eczema, psoriasis, the discoid rash of lupus, and granuloma annulare. When lesions occur in unusual locations on the body, diagnosis may be difficult. The lesions in lichen planus, however, are typically small and have a narrow border compared to granuloma annulare or the lesions that accompany infections. The presence of other autoimmune disorders in patients with characteristic purple skin lesions suggests a diagnosis of lichen planus.
Treatment
Treatment for lichen planus includes immunosuppressive agents such as acitretin prednisone and ultraviolet A-1 phototherapy.
Resources:
Gary White and Neil Cox, Lichen Planus and Lichenoid Disorders in Diseases of the Skin, Merck Medicus, 1999.
F Muller, W Groth, and G Mahrle, Multiple Autoimmune Syndrome. Reynolds-syndrome (acral scleroderma, primary biliary cirrhosis, Sjogren's syndrome) associated with the lupus erythematosus/lichen planus overlap syndrome. Hautarzt, May 2004: 465-470.
