Bullous lichen planus

Lichen planus is a chronic inflammatory and immune mediated disease that affects the skin, nails, hair, and mucous membranes. It is characterized by polygonal, flat-topped, violaceous papules and plaques with overlying, reticulated, fine white scale (Wickham’s striae), commonly affecting dorsal hands, flexural wrists and forearms, trunk, anterior lower legs and oral mucosa. Although there is a broad clinical range of LP manifestations, the skin and oral cavity remain as the major sites of involvement. The cause is unknown, but it is thought to be the result of an autoimmune process with an unknown initial trigger. There is no cure, but many different medications and procedures have been used in efforts to control the symptoms.Lichen planus lesions are so called because of their 'lichen-like' appearance and can be classified by the site they involve, or by their morphology.Although lichen planus can present with a variety of lesions, the most common presentation is as a well defined area of purple-coloured, itchy, flat-topped papules with interspersed lacy white lines (Wickham's striae). This description is known as the characteristic '6 Ps' of lichen planus: planar (flat-topped), purple, polygonal, pruritic, papules, and plaques. This rash, after regressing, is likely to leave an area of hyperpigmentation that slowly fades. That said, a variety of other lesions can also occur.Cutaneous LP is a self-limiting condition. It usually resolves within 6 to 12 months. Oral LP is a non infectious, chronic inflammatory condition that involves the oral mucosa and may be accompanied by skin lesions. The etiology of oral LP are unknown.Oral LP is considered to be a T-cell mediated chronic inflammatory tissue reaction that results in a cytotoxic reaction against epithelial basal cells. The inflammatory infiltrate in oral LP is primarily composed of CD8+ T cells. A potential pathway for CD8+ T cell-mediated cytotoxicity in oral LP is described as follows:Patient history and clinical presentation need to be taken to diagnose lichen planus. Patient with suspected cutaneous lichen planus needs to be evaluated clinically through patient interview and physical examination. Patients should be questioned about their medication history, any history of pruritus or genital pain and history of dysphagia or odynophagia. Examination of entire cutaneous surface including the scalp, oral cavity and external genitalia need to be included. Wickham’s striae often can be seen during microscopic examination of cutaneous lesions of lichen planus.The histologic findings of oral LP can offer strong support for the diagnosis, but are not pathognomonic. Clinical correlation is required. Common histologic findings of oral LP include:There is no cure for lichen planus, and so treatment of cutaneous and oral lichen planus is for symptomatic relief or due to cosmetic concerns. When medical treatment is pursued, first-line treatment typically involves corticosteroids, and removal of any triggers. Without treatment, most lesions will spontaneously resolve within 6–9 months for cutaneous lesions, and longer for mucosal lesions.Cutaneous lichen planus lesions typically resolve within 6 months to a year. However, some variant such as the hypertrophic variant might persist for years if left untreated or unmonitored.The overall estimated prevalence of lichen planus in worldwide population is  in the range of 0.2% to 5% .Lichen planus was first reported in 1869 by Erasmus Wilson.Apremilast is undergoing investigation as a potential treatment .