INTRODUCTION
Chloroquine (CQ) and hydroxychloroquine (HCQ), two well-known drugs among dermatologists, have shown their efficacy in the inhibition of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication.1,2 HCQ is found to possess a better clinical safety profile, more potency, and fewer drug–drug interactions compared to chloroquine.3 HCQ has been reported to exert efficacy in the inhibition of SARS-CoV-2 in vitro replication through diverse mechanisms. First, it interferes with the glycosylation of angiotensin-converting enzyme 2 (ACE2), resulting in a subsequent reduction in the binding efficacy between ACE2 on host cells and the SARS-CoV-2 spike protein. Second, it blocks the fusion of the virus to the host cell. Finally, it suppresses the “cytokine storm” accountable for the disease progression to acute respiratory distress syndrome (ARDS). Although studies are underway to confirm the in vivo effectiveness of HCQ in the SARS-CoV-2 infection, promising primary results have led to a shortage of the drug for dermatologic purposes, which is a real concern in the current pandemic.1
Lichen planopilaris is a form of primary cicatricial alopecia caused by lymphocyte infiltration obscuring the interface between the follicular epithelium and the dermis in the upper portion of the hair follicle.4 In later stages, perifollicular fibrosis and chronic inflammation (without interface changes) may also be observed. Ultimately, sebaceous glands and then follicles are entirely destroyed.4 Without treatment, LPP may cause significant hair loss with prominent psychological burden. The main goal of the treatment is to cease or reduce hair loss, control the symptoms (i.e., itching, burning, and tenderness), and mitigate the clinical signs of inflammation.4 To be effective, treatment should be started as soon as possible.5 Hydroxychloroquine (6.5 mg/kg/day or 200 mg twice daily) is considered an effective treatment in LPP, since it prevents antigen presentation by suppressing the interaction between the antigenic peptides and the class II molecules of the major histocompatibility complex (MHC), leading to a decreased cytokine production and inflammatory responses.6 It is commonly used as the first-line systemic therapy in LPP with some improvement in 55% of the patients.5,7 It may take 2–3 months to observe the primary clinical response with HCQ in LPP and 6–12 months to notice the maximal clinical effect of the drug.8 Partial response is a reasonable goal in patients with LPP. In spite of mitigating the inflammation and pruritus and negative pull test, hair count may continue to decrease due to subclinical hair loss.9
Lichen planopilaris is a form of primary cicatricial alopecia caused by lymphocyte infiltration obscuring the interface between the follicular epithelium and the dermis in the upper portion of the hair follicle.4 In later stages, perifollicular fibrosis and chronic inflammation (without interface changes) may also be observed. Ultimately, sebaceous glands and then follicles are entirely destroyed.4 Without treatment, LPP may cause significant hair loss with prominent psychological burden. The main goal of the treatment is to cease or reduce hair loss, control the symptoms (i.e., itching, burning, and tenderness), and mitigate the clinical signs of inflammation.4 To be effective, treatment should be started as soon as possible.5 Hydroxychloroquine (6.5 mg/kg/day or 200 mg twice daily) is considered an effective treatment in LPP, since it prevents antigen presentation by suppressing the interaction between the antigenic peptides and the class II molecules of the major histocompatibility complex (MHC), leading to a decreased cytokine production and inflammatory responses.6 It is commonly used as the first-line systemic therapy in LPP with some improvement in 55% of the patients.5,7 It may take 2–3 months to observe the primary clinical response with HCQ in LPP and 6–12 months to notice the maximal clinical effect of the drug.8 Partial response is a reasonable goal in patients with LPP. In spite of mitigating the inflammation and pruritus and negative pull test, hair count may continue to decrease due to subclinical hair loss.9
