The lichen nitidus was considered in its first descriptions at the beginning of the 20th century as an infectious granuloma. Since 1927 the similarity and sometimes coexistence of lichen nitidus and lichen planus (up to 8% of association, which is an important figure) were established. Since then, and to this day, the pathogenic separation, if any, of these two entities, has not yet been well established.
Lichen nitidus is a rare inflammatory dermatitis of unknown etiology and characterized by the appearance of multiple tiny, whitish papules with a shiny surface, usually asymptomatic.
Is Lichen Nitidus Contagious?
Lichen nitidus is not a contagious disease. It is a self-limiting disease that cannot be spread or transmitted to other people. It is a benign and chronic inflammatory skin condition that is usually harmless and resolve without treatment and leaves the skin without long-term effect.
There is some evidence to support the idea that lichen nitidus is a variant of lichen planus. First, there are well-documented cases of patients in whom lichen planus lesions coexist with lichen nitidus lesions. In addition, the initial lesions of lichen planus can be indistinguishable, both clinically and histopathologically, from those of lichen nitidus.
In any case, most researchers consider these two processes as two different entities and with enough clinical and histopathological personality to easily establish a differential diagnosis between both processes. In any case, as in lichen planus, the cause of lichen nitidus remains unknown.
The typical lesions of lichen nitidus consist of tiny papules, the size of a pinhead, with hemispheric morphology and a flat, shiny surface. Usually, the color of these papules is whitish and is usually asymptomatic.
Most lesions remain as isolated papules, although they tend to cluster in a certain anatomical region. They can settle in any area of the body surface, anterior thorax and abdomen and the gluteal region are the most frequently affected areas. Sometimes it is a generalized rash. The majority of cases occur in children or young adults and cases of family incidence have been reported. When the palms or soles are affected, the lesions show a different morphology and resemble dyshidrotic eczema or purpuric lesions. In these cases, only the presence of typical lichen nitidus lesions in other body areas and the histopathological study of the palmoplantar lesions allow establishing the correct diagnosis.
Rare forms of lichen nitidus include lesions of linear distribution or the development of lesions on previous scars as an expression of an isomorphic phenomenon.
The coexistence of lesions of lichen planus and lichen nitidus in the same patient is not rare, which supports the opinion that these are two morphological expressions of the same process. It also supports the relationship between these two processes, the fact that often patients with lichen nitidus show nail abnormalities, in the form of longitudinal grooves. However, mucous membrane involvement in patients with lichen nitidus is much rarer than in lichen planus.
The evolution of the lesions is variable, with cases of spontaneous involution in a few months and others of persistence for years, in spite of even a treatment with topical corticosteroids.
The diagnosis is confirmed by a skin biopsy. The histopathology of lichen nitidus lesions is characteristic; the papule is constituted by a dense inflammatory infiltrate located in an enlarged dermal papilla and immediately below the epidermal epithelium. This inflammatory infiltrate is mainly constituted by lymphocytes, histiocytes and it is not uncommon to observe some giant Langhans type multinucleated cell. Sometimes, there are also plasma cells as one of the components of the inflammatory infiltrate. The epidermis that covers this infiltrate is flattened and vacuolization is sometimes observed in its basal row.
Usually, no treatment is necessary, since the lesions of lichen nitidus are asymptomatic (do not produce symptoms) and self-limiting (they disappear in a certain period of time). In case of very extensive or very symptomatic lesions, good results have been obtained with topical corticosteroids or antihistamines.
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