White lesions of the vulva (sclerosing lichen planus of the female genitalia), vulvar condyloma acuminata, vulvar Bowens disease, etc. These chronic diseases cause itching of the vulva and localized skin and mucosal tissue changes. The main treatments available are topical hormonal medication, laser treatment and surgery. Although there are many traditional treatment methods, there are problems of recurrent disease and complications. Photodynamic therapy is a new non-invasive treatment technology researched and developed in recent years, with effective, safe and low recurrence characteristics, its clinical application in female vulvar diseases has been increasingly important. The author selected several cases of recalcitrant female sclerosing moss patients (who had failed with various traditional treatments) to be treated with 5-aminoketovaleric acid photodynamic therapy, and achieved satisfactory results, which are reported below. Case 1: Female, 56 years old. She came to our clinic in January 2010 with 8 years of vulvar leukoplakia, itching and burning pain. 8 years ago, white papules appeared on the perineum with no obvious cause and itching. Later, the rash gradually increased and spread to the labia majora and minora, clitoris and perineum, gradually dissolving into porcelain white patches and increasing itching. During the past 8 years, she used medium and strong glucocorticoid ointment [mometasone furoate ointment (trade name “Eloson”), compound dexamethasone acetate cream (trade name “Dermatoprene”), compound beclomethasone camphor cream (trade name “Wuji cream”) in outside hospital. “Testosterone propionate ointment, internal administration of ethylene estradiol, hydroxychloroform, two local injections of Depo-Provera, and physiotherapy with CO2 laser and liquid nitrogen freezing, all of which provided short-term relief, but relapsed soon after discontinuation. In December 2009, she underwent biopsy of vulvar lesions in the Department of Obstetrics and Gynecology of our hospital, which was consistent with vulvar sclerosing moss and excluded vulvar cancer and precancerous lesions. Dermatological examination: porcelain white skin damage was seen on the inner labia majora, labia minora and perineum, with irregular shape and clear borders, and mild increase in pigmentation of the surrounding skin. The labia minora shrinks and thins and fuses with the inner labia majora to completely disappear, and the vaginal opening is contracted and narrow. A 1.5 cm size fissure was seen at the perineum. The systemic examination was unremarkable. The patient was previously healthy, had been menopausal for 10 years, and had regular menstruation with moderate volume and normal color. In May 2010, photodynamic therapy was started. Treatment was given once every 2 weeks for 4 consecutive times. Three days after the first treatment, the patient complained of a significant reduction in itching and pain, and the erosive surface was covered with new epithelium at two weeks. After two treatments, the pruritus and pain almost completely disappeared and the erosion surface was completely healed. After three treatments, the lesion area was smaller than before, skin elasticity increased, painful defecation disappeared, and sexual life was available. After the fourth treatment, the itching and pain had completely disappeared, and most of the white spots had faded and pigmentation had been restored. Case 2: Female, 62 years old. She visited our department in June 2010 because of vulvar leukoplakia and intense itching for 3 years. 3 years ago, dark red spots with white patches appeared on vulva without any obvious cause, and the itching was unbearable, often making it impossible to sleep at night and accompanied by local pain after scratching. She had been treated with herbal rinses, sitz baths, herbal ointments and infrared irradiation at outside hospitals, but the treatment was not effective. In June 2010, she visited our outpatient clinic and underwent histopathological examination of vulvar lesions, excluding vulvar cancer and precancerous lesions, and was diagnosed as “vulvar sclerosing moss”. She was given “compound flumethasone ointment and halometasone ointment” for external use, fexofenadine for oral use and liquid nitrogen freezing, and her symptoms were relieved. However, because of the concern that the topical use of strong glucocorticoids might cause epidermal atrophy and secondary infection, he did not continue to use them and relapsed soon after stopping them. Photodynamic therapy was started in September 2010. The treatment method was the same as above, with 3 treatments. On the third day after the first treatment, the patient complained of significant relief of pruritus, which did not interfere with sleep. At one week, the pruritus basically disappeared. One week after the second treatment, most of the white spots on the labia majora and minora and perineum had faded, and the erythema gradually became lighter. Two weeks after the third treatment, the erythema of vulva had basically faded and the white spots had basically disappeared. At the 3rd and 6th month follow-up, there was no pruritus and no recurrence of skin lesions. Case 3: Female, 5 years old. Two years ago, the child’s family found that her vulva was erythematous, interspersed with white patches, erosion, itching, and painful during defecation. She was treated with topical medication at a local hospital with no significant effect. The symptoms gradually worsened, with intense scratching at night, often to the point that she could not sleep at night. In November 2011, her parents complained that her vulva itched severely and scratched vigorously at night, making it impossible for her to rest normally, and she complained of pain during defecation. Dermatological examination: the labia majora and minora were obviously red and swollen, eroded, interspersed with white patches, perineal and perianal maceration, thickened, and superficial fissures were visible. The parents refused to do a biopsy, and the clinical diagnosis was “sclerosing moss of the female genitalia”. Photodynamic therapy was given, and the treatment was the same as above. After one treatment, the pruritus was reduced. After two treatments, the redness and swelling subsided significantly and the erosion was basically healed, but the itching was recurrent. after three treatments, the redness and swelling subsided, the erosion was basically healed, and only a little white spot and maceration was visible around the anus, and the itching was significantly reduced and did not affect the night rest. a weak glucocorticoid ointment (hydrocortisone butyrate) was given topically, and oral cetirizine syrup could be controlled, and there was no recurrence after 3 months of follow-up. Sotiriou and Hillemanns treated 5 and 12 patients with persistent female sclerosing moss with ALA-PDT, respectively, and proved its safety and effectiveness. No recurrence at the 3rd and 6th month follow-up, which is basically consistent with what we observed. Photodynamic therapy utilizes the preferential aggregation property of photosensitizers on pathological tissue cells, and under the irradiation of light source of specific wavelength, the photosensitizers are excited to transfer energy to oxygen, which generates monomorphic oxygen and some reactive oxygen species to destroy the lesioned tissue by oxidation. Recently, Olejek conducted an immunological study on 100 patients with sclerosing lichen planus and found that the expression of CD34, MBP and CD44 in tissues increased significantly after PDT treatment compared with that before treatment. It is possible that PDT may also have a role in promoting angiogenesis (CD34) and restoring the function of keratinocytes (CD44) and neuronal cells (MBP) in the short term, and further studies are needed.