Lichen Planus: Tree moss on a flat and even surface…

Lichen Planus was first reported in 1869 by Erasmus Wilson.  The origin of the word Lichen is believed to be from the Greek word “Leichen”, which means tree moss and the Latin word “Planus” which means flat and even surface.  In 1895 Wickham further explained the characteristics of the lesions, now known as Wickham striae.  The coexistence of oral, cervical and stomach Lichen Planus was first described by Guogerot and Burnier in 1937.  A similar variant of mucosal Lichen Planus as the vulvovaginal-gingival syndrome with erosive lesions involving oral and vulvovaginal mucosa was introduced by Pelisse and colleagues in 1982.

So, what is Lichen Planus?  Lichen Planus is a common, pruritic, inflammatory disease of the skin, mucous membranes, and hair follicles.  It occurs throughout the world in all races.  It affects about one in one hundred people worldwide, mostly affecting adults over the age of 40 years.  About half of those affected have oral Lichen Planus, which is more common in women than in men.  About 10% have Lichen Planus of the nails.

The primary cutaneous lesions have features that are almost pathognomoic:  Small, flat-topped, polygonal papules (see below).  The color may be erythematous on onset but well developed lesions are violaceous (purple) in color.  On the surface there may be gray or white puncta or streaks (Wickham striae).  Oral mucosa may be involved demonstrating white, lacy or fern-like patterns.  There may be erosive involvement of the gums referred to as erosive lichen planus.  Rarely there may be bullous or hypertrophic forms.  Patients with Lichen Planus are susceptible to koebnerization (Koebner phenomenon), an isomorphic response where cutaneouos lesions appear in areas of skin trauma, such as a scratch (see below).

There are a variety of variants to include cutaneous (classic, bullous and hypertrophic), mucosal (oral and vaginal), lichen planopilaris, lichen planus of the nails, lichen planus pigmentosus and there is a form associated with medications.

ETIOLOGY:  Lichen Planus is a T cell-mediated autoimmune disorder manifesting with inflammatory cells attacking an unknown protein within skin and mucosal keratinocytes.  Contributing factors include genetic predisposition, physical and emotional stress, koebnerisation, localized skin diseases (such as herpes), systemic viral infections (hepatitis C), contact allergy and drugs such as gold, quinine, quinidine, etc.

TREATMENT:  Treatment is not always necessary but there are a variety of topical agents such as topical steroids, calcineurin inhibitors, tacrolimus ointment, pimecrolimus cream, retinoids and for those old school physcians, intralesional steroids may be effective.  Systemic therapies include acitretin, hydroxycholoroquine, methotrexate, azathioprine, mycophenolate mofetil, and phototherapy.  To read more about Lichen Planus click HERE, and HERE.