Annular atrophic lichen planus is a rare form of lichen planus, a chronic skin condition that causes an itchy, scaly rash. It is characterized by round, atrophic (thinned) patches of skin with a raised, scaly border. The rash may be red, purple, or brown in color. It is most commonly found on the arms, legs, and trunk, but can also occur on the face, scalp, and genitals. Treatment typically involves topical corticosteroids or other medications to reduce inflammation and itching.

The most common symptoms of annular atrophic lichen planus include:

-Raised, scaly, and itchy patches on the skin
-Patches that are lighter in color than the surrounding skin
-Patches that are ring-shaped or oval
-Patches that may have a smooth, shiny, or waxy appearance
-Patches that may be red, purple, or brown in color
-Patches that may be painful or tender to the touch
-Patches that may blister or form ulcers
-Patches that may be accompanied by hair loss in the affected area

The exact cause of annular atrophic lichen planus is unknown. However, it is believed to be related to an autoimmune disorder, where the body's immune system mistakenly attacks healthy cells. Other possible causes include exposure to certain medications, infections, and environmental factors.

The treatment for annular atrophic lichen planus depends on the severity of the condition. Mild cases may not require any treatment, while more severe cases may require topical or systemic medications.

Topical treatments may include corticosteroids, calcineurin inhibitors, retinoids, and vitamin D analogues. Systemic treatments may include oral corticosteroids, methotrexate, cyclosporine, and hydroxychloroquine. Phototherapy may also be used in some cases.

The exact cause of annular atrophic lichen planus is unknown, but certain risk factors may increase the likelihood of developing the condition. These risk factors include:

• Age: Annular atrophic lichen planus is more common in adults over the age of 40.

• Gender: Women are more likely to develop annular atrophic lichen planus than men.

• Stress: Stressful life events may trigger the condition.

• Certain medications: Certain medications, such as antimalarials, beta-blockers, and nonsteroidal anti-inflammatory drugs, may increase the risk of developing annular atrophic lichen planus.

• Exposure to certain chemicals: Exposure to certain chemicals, such as formaldehyde, may increase the risk of developing annular atrophic lichen planus.

At this time, there is no known cure for annular atrophic lichen planus. Treatment typically involves medications such as topical corticosteroids, topical calcineurin inhibitors, and oral medications such as retinoids, immunosuppressants, and antibiotics.