Abstract: 【Abstract】 Lichen planopilaris （LPP） and frontal fibrosing alopecia （FFA） are the two most common types of primary lymphocytic cicatricial alopecia in clinical practice, but their treatment poses significant challenges. These conditions are characterized by the replacement of hair follicle-sebaceous gland units with fibrous tissues, leading to irreversible destruction of hair follicles and ultimately resulting in scarring of the follicles. In recent years, with a deepened understanding of these two diseases, new treatment options have emerged in addition to traditional topical medications and systemic oral drugs, including novel topical small molecule drugs such as Janus kinase inhibitors. Based on the latest Chinese and international consensus as well as current clinical practice in China, the Hair Research Group of Chinese Society of Dermatology organized experts to develop a consensus on the etiology, pathogenesis, clinical manifestations, auxiliary examinations, diagnosis, differential diagnosis, and treatment of LPP and FFA after thorough discussions, aiming to further standardize the clinical diagnosis and treatment of these two conditions and provide a more scientific and authoritative reference.

Key words: Alopecia, Primary cicatricial alopecia, Lichen planopilaris, Frontal fibrosing alopecia, Diagnosis, Therapy, Consensus