Question: What is (are) Lichen planus pigmentosus ?
Answer: Lichen planus pigmentosus (LPP) is a rare form of lichen planus. It is characterized by oval or irregularly shaped brown to gray-brown macules and patches on the skin. Areas that are exposed to sun such as the forehead, temples and neck are most commonly affected. However, the macules and patches may also develop on the trunk or in places where two areas of skin touch or rub together (i.e. the armpit, groin, etc). LPP is a chronic, relapsing condition with periods of exacerbations (worsening symptoms) separated by periods of remission (a decrease in or disappearance of symptoms). Although the exact underlying cause of LPP is unknown, studies suggest that UV light, viral infections, and certain topical (applied to the skin) agents such as mustard oil and amla oil, may trigger the condition. Treatment for LPP is symptomatic.
Source: GARD

Question: What causes Lichen planus pigmentosus ?
Answer: What causes lichen planus pigmentosus? The exact underlying cause of lichen planus pigmentosus is currently unknown. However, studies suggest that the condition may be triggered by viral infections, UV light or the application of certain oils on the hair or skin (i.e. mustard oil, amla oil).
Source: GARD

Question: What are the treatments for Lichen planus pigmentosus ?
Answer: How might lichen planus pigmentosus be treated? Treatment for lichen planus pigmentosus is generally symptomatic and may include: Topical (applied to the skin) corticosteroids Topical calcineurin inhibitors (medications that are typically used to treat eczema) Skin lightening agents Laser therapy
Source: GARD