Introduction

Lichen nitidus is an uncommon chronic inflammatory skin eruption also known as a dermatosis. It is often asymptomatic and presents a self-limiting nature. However, symptoms and characteristics do consist of shiny, flat-topped, skin-coloured, pinhead-sized papules. They are usually found on the chest, abdomen, genitalia and upper extremities. This condition is common in all ages. Gender and race are not contributing factors.¹

Although it is seen asa benign condition and self-limiting, it is important to understand the progressive natural history and prognosis of the condition. This will enable future studies to be conducted and more accurate strategies to take place. For instance, treatment, management and identification. It is important to study rare dermatoses such as Lichen nitidus because there is a lack of awareness amongst clinicians. This can lead to delayed diagnosis, hence preventing treatment and management from being provided. As a result, misdiagnosis can occur and also worsen the condition.²

Overview of lichen nitidus

Aetiology and pathogenesis

There is a lack of knowledge about the genetic background of the condition. However, immune-mediated mechanisms, such as the involvement of T-lymphocytes, typically carry out a delayed reaction. Hence, the epidermal basal cells are noticed to be damaged in patients.³

Histologically, Lichen nitidus presents a distinct pattern, which generally involves a gathering of immune cells. The epidermal layer usually curves around the cluster of cells. This characteristic helps dermatologists to distinguish this skin condition from others, such as Lichenoid dermatoses (lichen planus).  For instance, cytokines and tumour necrosis factor-alpha (TNF-α) can continuously cause inflammation.⁴ 

Epidemiology

Lichen nitidus is a rare condition which can affect individuals at any age; however, it is most common in children and young adults. It is a benign condition that is noticed in both males and females with no ethnic or racial influence.¹ There is a lack of data on the global prevalence, particularly due to limited research in large-scale studies. This makes it difficult for diagnosis, and this can lead to problems arising with treatment. One of the main reasons is that most cases are asymptomatic. 

Clinical features

The clinical presentation consists of tiny, discrete, skin-coloured (pink papules) with a diameter of 1-2 mm that are commonly seen on individuals. Other features include flat-topped, shiny characteristics. They are typically seen on the genitalia, upper extremities and abdomen; however, they can also appear elsewhere on the body.⁵ 

The manifestation of the condition can be localised or generalised. Many cases are asymptomatic and can present with either mild or moderate pruritus, especially in widespread or inflamed lesions. Features may include the size of the lesion identified, the colour changes, where it has spread to and the location.⁶

Natural history 

Typical course

Lichen nitidus follows a benign course for around a few months to years. This appearance is self-limited, and treatment is not usually active. Characteristics of the condition consist of scarring or post-inflammatory hyperpigmentation. This can occur at recurrent rates.

Variants and atypical presentations

Symptoms are usually asymptomatic and have atypical variants. The most generalised form of Lichen nitidus is a widespread papule which presents a persistent and symptomatic prognosis. Additionally, palmoplantar variants affect the palms and soles. This variant presents hyperkeratotic papules, which can be mistaken for other dermatoses. Other variants can include linear, perforating, confluent and mucosal sun types. They are different in clinical and histological features.⁷

Triggers and associations

The underlying cause for the diagnosis of the condition remains unknown; however, research has identified that influential factors consist of:

• Systemic conditions such as Crohn's disease and Down syndrome
• Environmental or immunologic triggers such as viral infections and trauma. This can include EBV (Epstein-Barr virus) or hepatitis B⁸

Prognosis

General prognosis

The prognosis of Lichen Nitidus is usually resolved within months or a few years, which is beneficial as it does not worsen or cause further complications. Another benefit is that it does not progress into malignancy or damage the skin permanently.

There is typically minimal impact on daily functioning or quality of life, especially in asymptomatic individuals.⁹

Factors influencing prognosis

• Extent of skin involvement - can be resolved quickly when localised; however, if it is general, then treatment is not easily provided
• Degree of pruritus or discomfort - asymptomatic cases are common; however, itching or irritations can impact sleeping patterns, concentrations and the well-being of an individual
• Psychological or cosmetic concerns (e.g., genital lesions in adolescents) - scarring on visible regions can be embarrassing for individuals. Can lead to neuropsychiatric conditions such as anxiety or social withdrawal¹⁰

Long-term outcomes

Full recovery is common. Although it is not life-threatening and can be managed, in some cases, the condition may become chronic or recurrent.

When is treatment necessary? 

General approach

Active treatment is not provided as it is a self-limited condition and also due to its asymptomatic nature. Therefore, management is usually observed during the patient's time in an educational setting.¹¹

Indications for treatment

Treatment is still important despite the condition being non-life-threatening and self-limiting. 

• Symptomatic cases - although patients are more likely to be asymptomatic, there are cases where patients present with moderate to intense pruritus. This includes a progression and other symptoms to arise, such as sleep disturbances, skin excoriation or lichenification or secondary infections
• Extensive or generalised disease - it normally affects large areas of the body, such as the palms or the soles. This can further lead to hyperkeratosis. Individuals may find this concerning and impact their well-being. Not only is it a cosmetic concern, but it can also impair the function of that area. For instance, individuals may not be able to walk or use their hands properly to the best of their ability
• Involvement of sensitive areas -  this includes areas such as the genitalia or areas with mucous membranes. It can be painful and show a sense of discomfort. Daily activities can be impacted, such as walking or any sexual activity. This can lead to psychological distress due to embarrassment when with a partner
• Cosmetic or psychosocial distress - embarrassment of the lesions can lead to social withdrawal, anxiety or even depression¹²

Treatment modalities

• Topical Treatments: Topical corticosteroids are the first-line therapy typically for localised or symptomatic cases. They can reduce inflammation and help flatten papules. Corticosteroids may be used in combination with other immunosuppressive drugs such as tacrolimus or pimecrolimus
• Phototherapy: Narrowband UVB in generalised or refractory cases. They help to reduce lesion numbers and decrease symptom severity
• Systemic Treatments (rarely needed): Oral corticosteroids or retinoids in severe, widespread cases¹³

Alternative and supportive measures

Emollients can help individuals who present with dryness or irritation in the affected area. This is useful when utilised alongside active treatment. Other alternatives can be psychological support. They can help with emotional distress, especially those who are embarrassed by the visible or intimate locations.¹⁴

Conclusion 

Lichen Nitidus is a rare chronic self-limiting inflammatory condition. It presents with unique clinical and histological features which help with differentiation against other skin conditions. These lesions can impact individuals psychologically due to embarrassment if located in areas that are open to others to see.¹⁵ 

FAQs

Is lichen nitidus contagious?

No, it cannot be spread via skin contact or sharing items. It is an inflammatory condition and is not infectious. 

What are the causes?

It is an immune-mediated condition that is caused by the T-lymphocytes delaying their reactions. It may be triggered by viral infections, trauma or systemic conditions like Crohn’s disease or Down syndrome.

How is it diagnosed?

It is difficult to diagnose due to asymptomatic patients being more common; however, papule appearance helps with diagnosis due to the distinctive characteristics. 

Is it permanent?

No - it is self-limiting and can disappear and improve within months to a few years. 

Does it leave any scars?

No scars are left behind; however, post-inflammatory hyperpigmentation can be found. 

Who gets it?

Children and young adults typically present with this condition. However, it can affect individuals of any age. 

What are the treatments available? 

Treatment is not necessary due to its self-limiting nature; however, some symptoms may require treatment, such as itching, psychological distress and sensitivity in specific areas such as the palms, soles or genitalia. 

Is lichen nitidus related to lichen planus?

They are both lichenoid dermatoses, meaning they share similar histologic features, but they are distinct conditions.