Lichen planus is also known as dry occlusive glans. The incidence of anterior urethral stricture caused by it is increasing, and many doctors as well as patients are very curious why this disease occurs. Many international experts have studied the causes of mossy sclerosis with the same question in mind. Causes of mossy sclerosis First of all, a series of autoimmune diseases such as familial diabetes, pemphigus, albinism and thyroid disease have been found to be risk factors for the development of mossy sclerosis in men. Moreover, the increased level of anti-ECM-1 antibodies in male patients may be the result of autoimmune expression. Therefore, it is possible that the autoimmune problem in male patients is what causes the onset of mossy sclerosis. Second, scientists studying genes have found that human leukocyte antigen (HLA) DQ7 is often expressed in patients with lichen sclerosis. In addition, DR11 and DR12 were detected at increased levels in the blood of men with mossy sclerosis. So they propose a theory that mossy sclerosis may be related to genetic alterations in patients. Third, there is another argument that is more convincing. That is that mossy sclerosis of the male foreskin, glans and urethra is related to some injuries and chronic irritation. It has been found that mossy sclerosis of the perineal area occurs mostly in patients who have a history of perineal surgery and injury, while circumcision after birth is very rare. It can be reasoned that a moist, unclean environment due to circumcision may be a prerequisite for the development of lichen planus. Chronic local urinary irritation is also a damage factor that leads to the development of lichen planus. Fourth, infection is also a factor in the development of lichenoid sclerosis. The role of Borrelia spirochetes in the pathogenesis of lichenoid sclerosis has been given much attention. Immunological methods have found a 63% infection rate in patients with lichen sclerosis. It is even as high as 100% using PCR; EBV and HPV infections have also been reported in association. Fifth, hormonal changes. One study found that serum DTH levels were reduced in female patients with vulvar lichenoid sclerosis, suggesting that reduced expression of 5α reductase in the skin may be a factor in the cure of LS. Meanwhile, some scholars found that the expression of androgen receptors in the skin was absent in the progression of LS. In addition, oral estrogen administration in female patients may also induce the development of lichen planus. In conclusion, the factors that lead to urethral stricture in men with lichen planus are related to autoimmunity, infection and local chronic irritation, genes and altered hormone levels in the body.