Hydroxychloroquine is safe and efficacious in oral lichen planus: data from a large outpatient cohort.

Lichen planus (LP) is a chronic inflammatory T-cell mediated disease affecting the skin, mucous membranes and skin appendages. Data on clinical phenotypes and systemic treatment of LP are limited. We analyzed a cohort of LP patients (equal or older than 18 years) regarding their clinical phenotypes (subtype, demographics, comorbidities) and treatment. Patients were selected from 2017 to 2023 who were seen in our outpatient clinic during a treatment period of at least 2 years. We identified 85 patients (62 females, 73% and 76 above 50 years; 89%) who met selection criteria. 33 had oral LP (39%), 23 had cutaneous LP (27%) and 2% had both or other manifestations (32%). Frequent comorbidities were hypertension (n = 40), hypothyroidism (n = 17), asthma (n = 11), diabetes (n = 10) and dyslipidemia (n = 8). 44% were taking a medication known to favor LP onset. 2/85 patients had a malignant transformation. 33 patients were treated topically and 50 required systemic therapy. Hydroxychloroquine (HCQ) (n = 18; 36%) and retinoids (n = 17; 34%) were the most commonly used systemic medications. Both were efficacious as determined by the investigator global response reaching rates 78% and 71%, respectively. The tolerability of retinoids was lower than HCQ (adverse event rate 29% versus 6%). Our results confirm previous data on clinical phenotypes and comorbidity patterns in LP patients. The treatment assessment suggests that HCQ may be an efficacious and safe first-line treatment for mucosal lichen planus. Further data from prospective controlled clinical trials are needed to prove the optimal treatment approach for different clinical phenotypes of LP.