Lichen planus pigmentosus
Type of disease: Rare conditions
Lichen planus (LP) pigmentosus is a rare variant of lichen planus and is characterized by the presence of hyperpigmented, dark-brown macules in sun-exposed or skin-fold areas of the body. LP pigmentosus is a rare disease in Europe but it is common in Indian populations and in the Middle East. The disease usually appears in the third and fourth decade of life. The lesions usually do not cause symptoms. The exact cause of LP pigmentosus is unknown but various factors (e.g. viral infections and certain topical agents including mustard oil, amla oil and henna hair dyes) can trigger the disease. Lichen planus pigmentosus seems to follow a chronic and progressive course. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.