Lichen Amyloidosis: Causes, Symptoms, Diagnosis, and Treatment

Introduction:

Amyloidosis is a rare disease that is caused by the abnormal deposition of a protein called amyloid in various organs and tissues. Lichen amyloidosis is a type of amyloidosis that only affects the skin and does not involve other organs like other types. It is characterized by itchy patches on the skin with multiple small bumps and some lumps forming large lesions with a cobblestone appearance. The cause of lichen amyloidosis is still unknown, but it is mostly induced by scratching and scrubbing. It is more prevalent among Southern Chinese and South American populations and is more often seen in men than in women 50 to 60 years old. This article briefly explains lichen amyloidosis, its causes, clinical features, complications, and treatment.

What Is Amyloidosis?

Amyloidosis is a rare disease where abnormal proteins accumulate in organs or tissue, which leads to organ dysfunction. The organs that are affected are the heart, kidney, gastrointestinal tract, nervous system, and skin. Amyloidosis of the skin is known as cutaneous amyloidosis. In this condition, amyloid or amyloid-like proteins are deposited in the skin.

Types of amyloidosis:

1. Localized amyloidosis (primary cutaneous amyloidosis).

• Lichen amyloidosis.

• Macular amyloidosis.

• Biphasic amyloidosis.

• Nodular amyloidosis.

2. Systemic amyloidosis.

3. Hereditary amyloidosis.

What Is Lichen Amyloidosis?

Lichen amyloidosis is the most common subtype of primary cutaneous amyloidosis. It accounts for about 10 percent of primary cutaneous amyloidosis cases. It is a skin condition in which abnormal proteins called amyloids build up in the upper two layers of the skin.

The condition is typically characterized by a severe, itchy patch with multiple small bumps on thickened skin. These patches are commonly seen on anterior legs but can also be seen in forearms, thighs, and other parts of the body. The cause of lichen amyloidosis is still not fully understood, but it is mostly induced by scratching and scrubbing.

What Causes Lichen Amyloidosis?

The exact cause is still not completely known but long-term scratching, familial link, and gene mutation are likely known to be the cause of lichen amyloidosis.

• Long-Term Scratching: Due to scratching the skin, the skin cells (keratinocytes )get damaged and the damaged keratinocytes release an abnormal protein called keratin that misfolds and clumps together to form amyloid deposits.

• Familial Link and Mutation: 10 to 15 percent of cases have a familial tendency, and some studies have shown lichen amyloidosis is caused by a mutation in IL-31rA or (OSMR) genes (involved in immune system response like inflammation, and self-destruction of cells).

What Are the Common Signs and Symptoms of Lichen Amyloidosis?

The signs and symptoms of lichen amyloidosis include:

• Intense itching.

• Red and scaly patches on the skin with multiple small bumps.

• Bumps show a rippled pattern.

• Thickened skin.

• Commonly seen on anterior legs.

• Some bumps come together, forming large lesions with a cobblestone appearance.

Who Gets Lichen Amyloidosis?

Lichen amyloidosis is thought to be more common among Southern Chinese and South American populations. It is more prevalent in men than in females and occurs primarily in persons 50 to 60 years of age.

What Are the Complications of Lichen Amyloidosis?

Lichen amyloidosis is a benign condition that does not extend to other parts of the body or internal organs but can cause psychological distress due to skin disfigurement and itching. Also, intense itching with bleeding due to aggressive scratching.

How Is Lichen Amyloidosis Diagnosed?

Diagnosing lichen amyloidosis involves a thorough examination of the skin lesions by a dermatologist and a skin biopsy if required.

• Clinical Evaluation: The dermatologist performs a thorough examination and checks for skin lesions and symptoms like itchy, red, and scaly patches on the skin with multiple small bumps that are associated with lichen amyloidosis.

• Skin Biopsy: A biopsy is done to confirm the diagnosis. In a biopsy, a small tissue taken from the skin is examined under a microscope to check if there are any amyloid deposits.

What Is the Differential Diagnosis of Lichen Amyloidosis?

Lichen amyloidosis, particularly in its early or mild stages, can be challenging to distinguish from other itchy, papular skin conditions like:

• Nodular Prurigo: A long term inflammatory skin condition characterized by itchy rashes that appear on arms, legs, back, and abdomen.

• Hypertrophic Lichen Planus: An inflammatory skin condition that appears as itchy bumps on skin.

• Lichen Simplex Chronicus: A skin disorder characterized by thick and leathery patches on skin that occurs due to repeated rubbing or scratching.

• Pretibial Myxoedema: Pretibial myxoedema is a form of graves' disease (a thyroid disorder).It presents as a thick, scaly plaques on lower legs.

• Pretibial Pruritic Papular Dermatitis: A skin disorder that presents with itchy and raised bumps on lower legs.

How Can One Prevent Lichen Amyloidosis?

Some preventive measures can be taken by individuals to reduce the severity of the condition, which include:

• Avoid Scratching: Scratching and scrubbing can aggravate lichen amyloidosis, so avoid rubbing or scratching the skin.

• Moisturizer: Moisturizers prevent dryness and itching.

What Is the Treatment of Lichen Amyloidosis?

Although there is currently no cure for lichen amyloidosis, recurrence is common with current treatments, but some treatment options are available that provide relief from itching and disfigurement.

Topical Treatment:

• Corticosteroids available in ointments are widely used and are very effective in treating lichen amyloidosis, especially when used under a dressing.

• Calcineurin inhibitors come in creams and help in less severe cases.

• Retinoids are very effective in widespread lesions. They reduce the severity of the condition.

• Dimethyl sulfoxide (DMSO 10 percent), and menthol two percent.

• Antihistamines help in minimizing the itching.

• Intralesional corticosteroid injection or cryosurgery with or without topical steroids.

Systemic Treatment:

• Oral retinoids.

• Immune modulators.

Physical Treatment:

• Phototherapy: PUVA and narrow-band UVB reduces the itching.

• Laser therapy: Fractional CO2, Er: YAG, Nd: YAG, and Pulse Dye Laser removes lesions to a great extent.

• Dermabrasion, cautery curettage, or excision (depending on the location and extent of the lesion).

Conclusion:

Lichen amyloidosis is a rare skin condition characterized by itchy patches with multiple small bumps. It is mainly induced by scratching and scrubbing and is the most common subtype of primary cutaneous amyloidosis. The exact cause is unknown, but long-term scratching, familial link, and gene mutation are likely known to be the causes. It is more common among Southern Chinese and South American populations and is more prevalent in men 50 to 60 years old. Currently, there is no cure for lichen amyloidosis, but there are some treatment options available that provide relief from itching and disfigurement. Early diagnosis and available treatment can help individuals to improve their overall well-being. If experiencing symptoms of lichen amyloidosis, consult a dermatologist for further evaluations.