Causes of lichen planus pigmentosus

This condition can produce slate-grey, brown, or darker patches, often on the face, neck, or folds, with little surface scale. Inflammation may be subtle, and some people notice itch or mild sensitivity before or during the colour change. Sun exposure, friction, cosmetics, or a contact reaction may contribute in some cases, but a dark patch has many possible explanations. A clinician compares its shape, borders, distribution, and progression with other pigment disorders and may examine the skin closely or take a sample.

Colour can remain after inflammation settles because pigment may sit deeper in the skin. That does not identify the original trigger by itself.

Use broad sun protection, avoid rubbing or bleaching products, and stop a newly introduced cosmetic if it clearly irritates the area. Photographing the patch in consistent light can help show change over time. Treatment is individualised; a dermatologist may consider topical corticosteroids when active inflammation is present, while oral corticosteroid treatment is reserved for selected situations. Avoid self-treating an undiagnosed dark patch.

Book a dermatology review for new, spreading, itchy, or changing pigmentation, especially when its cause is unclear. Seek earlier assessment if a patch becomes painful, ulcerated, bleeds, forms a distinct lump, or changes quickly; those features need direct examination.

Ask whether the pattern fits lichen planus pigmentosus, whether a product or friction could be contributing, and whether a biopsy is appropriate. Ask how to protect the area from light, what improvement would look like, and how to monitor for new changes.