What is lichen nitidus?

Pinkus first discovered Lichen Nitidus (LN) in 1907. It is caused in response to inflammation and often appears in the form of papules (bumps on the skin) spread across the hands, chest, abdomen, and genital areas. Most people do not have any symptoms, and it heals on its own.² Although it is seen in children mostly, it can appear in young adults, and rarely in older adults as well, with equal prevalence in both males and females.²

What causes it?

The cause of Lichen nitidus is unknown, although genetic factors may be responsible for its development.³ It can occur in multiple family members, including in identical twins.³ There have been possible links between HLA alleles and LN.⁴ 

Lichen planus and Lichen nitidus share similar origins but different features.⁴ It has been correlated with diseases such as Atopic dermatitis, Crohn's disease, Down's syndrome, Amenorrhea, and an advanced form of HIV. Additionally, it is also found in people who have tattoos.³ These associations suggest that there may be shared underlying genetic or immunological mechanisms between Lichen nitidus and these other diseases.

Mechanism

The exact mechanism behind it is still unclear; however, it is believed that an immune-mediated mechanism is involved in causing LN.² A foreign body (an allergen) causes a cell-mediated response, activating the defence system of the body and releasing lymphocytes (to fight the allergen), which accumulate and form inflammatory papules. This is an exaggerated, inflammatory, and immune-mediated response to a foreign body.² Even viruses, bacteria, and infectious agents can cause this cell-mediated response. LN is often associated with skin diseases like lichen planus, vitiligo, and erythema nodosum.⁴

Clinical characteristics seen in children

• Appearance: shiny, separated and multiple skin-coloured, white or pink bumps with a flat top, visible as light spots on dark skinned people
• Size: 1 to 2 mm in diameter, pinhead or pinpoint sized
• Shape: round or polygonal
• Location: neck, hands, abdomen, buttocks, and penis area
• Rare locations: palms, nails, soles of the feet, and mouth 
• Mouth: greyish-white papules
• Location in the mouth: tongue and the inner part of the cheek
• Nail: The edges of nails have pitting or splitting, or there is ridging seen on the nail plate and thickening around nail folds
• Rare symptoms: mild itching and rash 
• Rare forms: blisters, vesicles, or papules with central depression
• Hallmark: Koebner phenomenon, also called the Isomorphic phenomenon, where the disease mimics an injury or a burn.² LN papules are seen around sites of stretch marks, arranged in a line

• It has multiple variants; for instance, it can appear in a linear form (papules forming lines), as blood-filled red spots (haemorrhagic), confluent or perforating types, and even spinous or reticulated forms.²
• Other Variants:⁴
  • Generalised form
  • Purpuric form, where the papules start appearing in the feet and ankles and then progress to the legs 
  • Vesicular (blistering) 
  • Actinic lichen nitidus has a seasonal appearance (seen more often in summer) and affects parts of the skin exposed to sunlight
  • A keratoderma seen on palms and soles, which looks similar to eczema

Diagnosis

• Diagnosis is done by a healthcare provider, such as a doctor or a specialist (dermatologist)
• Diagnosis is based on a close examination of the body parts for bumps and their appearance
• Biopsy (some part of the affected skin is removed to be examined under a microscope): a ‘claw-and-ball‘ appearance confirms Lichen nitidus⁵
• Dermoscopy is useful in differentiating LN from other skin conditions.⁶ A device similar to a magnifying glass is used to visualise the skin closely and examine the papules

Differential diagnosis

Complications

These bumps, if dark-coloured, can be worrying for adolescents because they are visible and may alter their physical appearance. Otherwise, there are no known complications associated with LN.²

Course and prognosis

• Rare and self-limiting
• Associated with lichen planus¹¹
• Heals in a few weeks or persists and does not respond to medications
• In children who have generalised skin lesions, the resolution is difficult to predict
• In most cases, it resolves in months or within a year¹¹

Management

• Resolves by itself in most people²
• If the bumps are persistent or widespread, or if itching is present, then medications should be considered. 
• Anti-allergic drugs are provided to relieve itching 
• Topical and systemic steroids: oral tablet of Prednisolone/0.05%, Fluocinonide cream have been proven to cure mild LN⁴
• Ultraviolet A and B treatment: for bumps in upper and lower extremities, and for those who don't respond to tablets¹²
• No recurrence was seen after using Cyclosporine tablets for LN bumps, as per a few studies¹³
• Injections of Isotretinoin for widespread bumps have also been used¹⁴ 
• Immunotherapy: Dinitrochlorobenzene, Retinoids, Isoniazid, and Itraconazole have also been effective in treating generalised papules and in severe symptoms¹⁴  

Follow-up

• The frequency of follow-up visits depends on the patient’s response to therapy.
• It is important to monitor for side effects of drugs like steroids and immunosuppressant drugs, especially in children.
• Some school-age children can develop low self-esteem if the bumps are visible, and hence, the psychological impact of these skin problems should not be neglected.

Awareness - patient education

Doctors should ensure that parents of young patients are aware that LN is harmless, not contagious in nature, and resolves on its own.²  This is to prevent unnecessary treatments and the risk of side effects that different treatment modalities can cause. Only if LN persists, and the child has symptoms of it, or if it is cosmetically unpleasing, then the doctor should discuss different treatment options.

An inter-professional team involving a dermatologist and a pharmacist should guide parents of affected children or young adults on dosing and side effects of medicines, if they are to be included in the treatment plan.²

Summary

Lichen Nitidus is a rare and self-limiting condition that mainly affects children. The diagnosis depends on differentiating it from other skin conditions through a biopsy. Most cases require minimal intervention, but further long-term studies are required in the younger population to understand the possible mechanisms behind it.

FAQs

Is it contagious?

No, LN is an inflammatory skin condition, and it does not spread to other people. It also doesn't spread to other parts of the body.

Can you do your regular activities with Lichen nitidus?

Yes, most people do not develop any symptoms, and they can continue doing their regular day-to-day activities. In rare cases, mild itching and a rash are seen.

Can you prevent Lichen nitidus?

No, it cannot be prevented. The exact cause is unknown, but it is associated with genetic factors, environmental factors and can be associated with diseases like Lichen planus and Crohn's disease.

When should you call a doctor if you see a skin bump?

If the skin bump has occurred without any reason (not allergy-related) and doesn't go away with topical moisturisers, it is advised to see a doctor or check on the NHS website.