Flat-topped papules on a child’s trunk

Lichen nitidus is an idiopathic eruption characterized by multiple, 1- to 2-mm, flat-topped, skin-colored papules. Lesions are usually localized and commonly affect the penis, lower abdomen, medial thighs, flexor wrists, or dorsal hands and forearms.They also often demonstrate Koebner phenomenon...

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Lichen nitidus is an idiopathic eruption characterized by multiple, 1- to 2-mm, flat-topped, skin-colored papules. Lesions are usually localized and commonly affect the penis, lower abdomen, medial thighs, flexor wrists, or dorsal hands and forearms.

They also often demonstrate Koebner phenomenon or “isomorphic response,” which refers to the appearance of lesions in a linear array. Koebnerized lesions of lichen nitidus are found most frequently on the penis, forearms, and dorsal hands.¹

Lichen nitidus is usually asymptomatic but pruritus occasionally may occur. Color variations have been reported, including reddish lesions with variable hues of yellow, brown, and violet.¹ In darkly pigmented individuals, the lesions may be hypopigmented or hyperpigmented.²

A central depression occasionally is present.² Lichen nitidus is self-limited but because resolution often takes years, some authors consider it to be a chronic disease. 


Many clinical variants of lichen nitidus have been reported including generalized and actinic subtypes. It is believed that pruritus is a more common complaint in the generalized variant.¹ The actinic variant affects the sun-exposed areas of the dorsal hands, brachioradial area, posterior neck, and face.

Actinic lichen nitidus has been reported in the literature under other names including “summer actinic lichenoid eruption” and “pinpoint, papular polymorphous light eruption.”¹ 

Other less frequently reported variants include vesicular, hemorrhagic, purpuric, and spinous follicular lichen nitidus.¹ A linear variant of lichen nitidus has also been reported, but it seems an arbitrary distinction because all forms of the eruption may demonstrate linear arrays from the Koebner phenomenon. 


Lichen nitidus has also been reported to solely involve the palms and soles, presenting with multiple tiny hyperkeratotic papules that may coalesce to form diffuse hyperkeratotic plaques that fissure.¹ A distinctive feature of lichen nitidus of the palms and soles is the appearance of a keratotic plug in the center of lesions.¹ 

The disease also may involve the nails, with reports of pitting, longitudinal ridging, and nail-fold inflammation.¹ Other nail changes including terminal splitting and increased longitudinal linear striations, and periungual involvement, have been noted.² 


Rarely, oral involvement may be seen with lesions on the hard palate, soft mucosa, or tongue.^1,2 Oral lesions have been described as gray-yellow papules, petechiae, or white plaques.^1,2 


Lichen nitidus is considered to be a relatively rare entity, although that may be due to underreporting. Strong epidemiologic statistics do not exist, but lichen nitidus is reported more frequently in children and young adults. Familial cases have been rarely reported.¹ 

The generalized variant tends to occur more frequently in females and has been reported in association with Down syndrome.³ The actinic variant is very rare, with fewer than 20 cases reported in the literature. It occurs almost exclusively in Fitzpatrick skin types IV-VI, with cases reported from the Middle East and the Indian subcontinent and in African-Americans.¹ 


The pathogenesis of lichen nitidus is unknown.¹ It was formerly believed to be a variant of lichen planus, but that is no longer believed to be the case because the clinical presentation and histology are distinct.² 

It was also hypothesized that lichen nitidus was a tuberculous lesion or tuberculid, but subsequent animal studies have since debunked that idea.² Lichen nitidus has been reported after hepatitis B immunization and during treatment of hepatitis with interferon-α.²

Because lichen nitidus has been reported in association with Crohn disease, which is also notable for granulomatous inflammation, investigators hypothesize that the two conditions may share a common underlying mechanism.²

Diagnosis of lichen nitidus is often made on clinical grounds alone. However, when indicated, a skin biopsy is diagnostic because the histopathologic findings of the disease are unique. The “ball and claw” configuration, in which hyperplastic rete ridges extend or form a “claw” around a dense, “ball-like” infiltrate of lymphocytes, epithelioid cells, and occasional Langerhans cells, is pathognomonic for lichen nitidus.¹

The overlying epidermis is often attenuated and may show a central parakeratotic “cap.”^1,2 Liquefactive degeneration of the basal layer is often seen and can be associated with incontinence of melanin pigment, Civatte bodies (degenerated collagen), and a Max-Joseph-like space (focal separation of dermis from epidermis due to the liquefactive degeneration).² 


Immunohistochemical studies have shown a predominance of CD4-positive T cells over CD8-positive T cells, and the presence of large numbers of CD1-positive Langerhans cells in dermal infiltrates.² The significance of these immunohistochemical findings is unknown. 


The differential diagnosis of lichen nitidus includes lichen planus (LP), flat warts, frictional lichenoid dermatitis, and papular eczema, especially in darkly pigmented individuals.² Flat warts, frictional lichenoid dermatitis, and papular eczema can be easily distinguished from lichen nitidus with a skin biopsy.

Distinguishing lichen planus from lichen nitidus can be difficult both clinically and histologically; however, the diagnosis of lichen nitidus is favored clinically if the lesions are uniform in size, the color is not violaceous, and Wickham’s striae (reticulated white areas) are absent. Histologically, no deposits of immunoglobulin are seen in the dermal papillae with lichen nitidus, whereas they are present in lichen planus.² 


As mentioned previously, lichen nitidus is self-limiting, so no treatment is necessary. In a study of 43 patients two-thirds of cases resolved in a year or less, with the longest duration reported at 8 years.^2,4

For the treatment of pruritus, topical corticosteroids and oral antihistamines are the mainstays. Anecdotal reports exist of topical calcineurin inhibitors (i.e., tacrolimus, pimecrolimus) as an effective therapy in children.²

Narrowband ultraviolet B (UVB) or phototherapy (PUVA) in addition to oral retinoids (acitretin and etretinate) also have been reported to be beneficial. However, because lichen nitidus is self-limiting, it is likely that the benefit ascribed to these therapies is a result of the natural history of the disease rather than the interventions. 


Our patient was asymptomatic and his mother was not bothered by the appearance of the lesions, so no treatment was initiated. The patient was lost to follow-up.

Audrey Chan, MD, is a third-year dermatology resident at Baylor College of Medicine in Houston. 


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