Introduction: Recent expert recommendations suggest mycophenolate mofetil (MMF) as a third-line therapy, in severe corticosteroid-dependent or corticosteroid-resistant nail lichen planus (NLP). However, there is currently no literature to support MMF use in this indication. This is a retrospective monocentric French case series of 5 patients with severe corticodependant or corticoresistant NLP treated by oral MMF (2–3 g/day), between 2013 and 2021. Case Presentation: The primary outcome was therapeutic success in a target fingernail. All 5 patients showed some clinical improvement, ranging from mild improvement (1/5) to clinical cure (2/5). Clinical improvement was more significant when the drug was taken for a longer period (24 months vs. 4 months) and at a higher dose (3 g/day vs. 2 g/day). Relapse occurred after stopping or tapering the MMF dose. MMF was well tolerated. Discussion/Conclusion: MMF may be a treatment to consider for severe corticosteroid-dependent or corticosteroid-resistant NLP. The long-term safety of this treatment warrants further investigation.

Established Facts

  • Nail lichen planus (NLP) can cause irreversible lesions (pterygium, anonychia) with functional and psychological consequences. Treatment options remain limited, lack sustained efficacy, and are primarily based on intramuscular and/or intralesional potent corticosteroid injections.

  • Based on reported mycophenolate mofetil (MMF) efficacy in mucocutaneous lichen planus, recent expert recommendations suggest its use as a third-line therapy in severe NLP. However, there is currently no literature to support MMF use in this indication.

Novel Insights

  • We here report a case series of severe corticosteroid-dependent or corticosteroid-resistant NLP treated with MMF.

Lichen planus (LP) is a chronic inflammatory disorder of unknown origin which can affect skin, scalp, mucosal membranes, and nails [1]. Nail LP (NLP) can be either isolated or associated with other sites’ disease. The diagnosis is based on pathognomonic clinical features. When a nail biopsy is performed, histology reveals a band-like inflammatory cell infiltrate at the dermoepidermal junction. NLP poses a particular therapeutic challenge because damage to the nails can lead to irreversible lesions, such as nail pterygium and anonychia, with functional and psychosocial consequences. Therefore, early diagnosis and treatment are critical, especially in severe forms. Treatment options remain limited, lack sustained efficacy, and are mainly based on intramuscular and/or intralesional potent corticosteroid injections. Based on the reported efficacy of mycophenolate mofetil (MMF) in mucocutaneous LP [2, 3], recent expert recommendations suggest MMF as a third-line therapy, in severe corticosteroid-dependent or corticosteroid-resistant NLP [4]. However, there is currently no literature to support MMF use in this indication.

We retrospectively reviewed 5 patients diagnosed with severe corticodependant or corticoresistant NLP, treated with oral MMF. All patients were treated and evaluated in the Department of Dermatology of Bordeaux University Hospital, France, between 2013 and 2021. Patients were monitored with regular clinical examination and blood tests during the first 6 months following the initiation of MMF. Risk of drug-drug interactions was assessed before MMF prescription to ensure there was no contraindication [5]. According to recent expert recommendations [4], response to treatment was graded in a target fingernail as: no improvement, “minimal improvement” for a disease reduction of <25%, “mild improvement” for a disease reduction of 26–50%, “moderate improvement” for a disease reduction of 50–75%, “great improvement” for a disease reduction of 76–99% and “clinical cure” for a disease reduction of 100%.

Clinical characteristics of patients are described in Table 1. We identified 4 men and 1 woman, aged 51–70 years. The diagnosis of NLP was confirmed by nail biopsy for 3 cases. Only 2 cases had extra-ungual LP, consisting in lichen planopilaris with secondary cicatricial alopecia and mucocutaneous LP. Two patients had experienced prior failure to one or more non-steroidal drugs, including: acitretin (20 mg/day) and/or cyclosporine (5 mg/kg/day). Patients were treated with MMF, as a monotherapy, at a daily dose ranging from 2 g/day to 3 g/day. The time from initiation of MMF treatment to the last follow-up was 4–96 months.

Table 1.

Details of patients treated with MMF for severe corticodependant/corticoresistant NLP (n = 5)

Details of patients treated with MMF for severe corticodependant/corticoresistant NLP (n = 5)
Details of patients treated with MMF for severe corticodependant/corticoresistant NLP (n = 5)

All 5 patients showed some clinical improvement, ranging from mild improvement (1/5) to clinical cure (2/5) (Fig. 1). Extra-ungual disease also responded well to MMF treatment and secondary cicatricial alopecia remained stable. Clinical NLP improvement was more significant when MMF was taken for a longer period (24 months vs. 4 months) and at a higher dose (3 g/day vs. 2 g/day). Compared to the use of MMF in atopic dermatitis, treatment duration and required dose to achieve clinical improvement were, respectively, longer (4 months vs. 2 months) and higher (3 g/day vs. 1–2 g/day) in NLP [6]. There is no data in the literature regarding nail growth in NLP, but 3–6 months is thought to be a reasonable treatment period before evaluating clinically relevant results [4]. Interestingly, not all affected nails responded to therapy and among fingernails, thumb nails seemed to respond less. Given the heterogeneous therapeutic response within individual patients, we hypothesize that clinical response under MMF treatment also depends on clinical nail features. Thus, severe non-scarring nail involvement might require an even more prolonged treatment (>1 year) to achieve disease remission.

Fig. 1.

Clinical features of NLP before and after MMF treatment in patients 1, 2, and 5.

Fig. 1.

Clinical features of NLP before and after MMF treatment in patients 1, 2, and 5.

Close modal

In our case series, 2 patients experienced flares a few weeks after stopping MMF or when the dose was reduced (2 g/day). MMF was well tolerated, without severe infectious or gastrointestinal side effects.

This case series suggests that MMF may be a treatment to consider for severe corticosteroid-dependent or corticosteroid-resistant NLP. The long-term safety of MMF prescription in NLP warrants further investigations since this study suggests long-term prescription is needed to prevent subsequent flares of the disease.

The authors have no ethical conflicts to disclose. Patients have given written informed consent to publication of the details of their medical case and any accompanying images. In France, Ethics Committee approval is not required for access to clinical files by the hospital staff for purposes of improving patient management or internal evaluations of practice.

The authors have no conflicts of interest to declare.

This study received no external funding.

Dr. A. Duplaine is the guarantor of the content of the manuscript, including the data and analysis. Dr. O. Cogrel contributed to data collection, data analysis and interpretation, and drafting of the manuscript.

All data generated or analysed during this study are included in this article. Further enquiries can be directed to the corresponding author.

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