INTRODUCTION

LPP is an aesthetically distressing pigmentary disorder that often presents a therapeutic challenge [1].

Few efficient therapeutic approaches have been proposed, particularly systemic treatments [2].

Tranexamic acid (TXA) and oral retinoids, in addition to long-known topical and laser treatments, represent an emerging therapeutic option and could offer a novel approach to LPP treatment.

The primary objective of this study was to determine the efficacy and tolerance of TXA and/or oral retinoids on the pigmentary component of lichen planus pigmentosus (LPP).

MATERIALS AND METHODS

A prospective study was conducted between January 2020 and December 2024, including patients diagnosed with pigmented lichen planus (LPP).

RESULTS

We included 39 patients (38 women and 1 man) with a mean age of 47.38 years (23–64 years). A history of sun exposure was reported in 26 cases.

More than half of our patients had potential triggering factors such as hair dyes, oils, black soap, and scrubbing (53%).

According to the Fitzpatrick scale, 28 patients had phototype 4, followed by 8 patients with phototype 3, and the other three with phototype 5.

The face was the initial site in all patients, followed by the neck. The cheek area was affected in nearly 90% of the cases, followed by the chin and forehead.

Other affected areas included the lips, periorbital zone, and temples.

A biopsy was taken in 21 patients.

An association with autoimmune diseases was observed in 12 patients, including lupus, diabetes, dysthyroidism, and Gougerot’s disease.

Twenty patients had other associated dermatoses, such as rosacea, acne, periorbital hyperpigmentation, and post-inflammatory hyperpigmentation. Two patients had associated ochronosis.

Associated frontal fibrosing alopecia was noted in 21 cases, accounting for approx. 54% of the cases.

All patients received local treatment with azelaic acid, kojic acid, Kligman’s trio, or other depigmenting topical treatments.

Eight patients underwent vascular laser therapy due to a visible vascular pattern, clinically and dermoscopically.

Nearly half of our patients (20) were treated with low-dose oral retinoids (10 or 20 mg), with an average duration of 12 to 18 months, extending up to 36 months in some cases.

Eight patients received oral TXA at 500 mg per day, divided into two doses, for an initial duration of 4 months, followed by maintenance therapy lasting up to 12 months in some cases.

Eleven patients received combined oral retinoids and tranexamic acid (Table 1).

Table 1: Efficacy of molecules alone or in combination in lichen pigmentosus.

Most patients were followed up at 3 and 6 months, and efficacy was assessed both clinically and dermoscopically.

A satisfactory outcome was observed in three individuals, with a significant improvement of over 50% (Figs. 1 and 2).

	Figure 1: Good improvement after the combination of retinoids and TXA, also combined with topical treatment and laser, a) before and b) after.
	Figure 2: Good improvement after using retinoids and tranexamic acid for one year a) before and b) six months after stopping treatment.

Moderate improvement (26–50%) was seen in 17 patients.

Mild improvement was noted in 15 cases, while 4 patients showed no improvement.

In our sample, the highest efficacy was found in the group treated with the combination of TXA and low-dose retinoids.

No major side effects justified treatment discontinuation.

Minor symptoms included dry mouth due to retinoids, digestive disturbances, and oligomenorrhea.

DISCUSSION

Lichen plan pigmentosus (LPP) is an uncommon variant of lichen plan, often linked to mosaic genetic alterations. Clinically, it presents as dark brown to grayish macules, primarily in photo-exposed areas, often accompanied by pruritus [3].

Dermoscopy plays a crucial role in differentiating LPP from other pigmentary disorders such as melasma, ochronosis, and pigmented amyloidosis.

Dots and globules in different arrangements, along with the accentuation of the normal pseudonetwork, are the principal dermoscopic features of LPP; and blotches are indicative of a long-duration disease [4].

Histopathological examination reveals epidermal atrophy with vacuolar degeneration of the basal cell layer. The dermis shows pigmentary incontinence with dispersed melanophages and a mild follicular or perivascular inflammatory infiltrate. While LPP and erythema dyschromicum perstans share similar histopathological features, they present distinct immunological and clinical characteristics [5].

This condition predominantly affects women, typically beginning in the third or fourth decade of life, and is more common in individuals with darker skin tones [6].

Suspected triggering factors include sun exposure and certain photosensitizing substances, such as mustard oil, henna, and specific hair dyes.

The exact prevalence of LPP remains unknown [1]. In our study, women were more affected than men, which in our sample could be explained by the more frequent use of cosmetics, oils, and scrubbing among women.

LPP is frequently observed alongside frontal fibrosing alopecia in individuals with darker skin tones, suggesting a shared pathological mechanism affecting the interfollicular epidermis rather than a coincidental association. This association may provide new insights into the etiology of the condition [7].

Treatment may help control disease progression; however, the pigmentation remains persistent and may take months or even years to fade gradually [8].

The therapeutic management of LPP is often complex due to the lichenoid inflammatory reaction and pigmentary incontinence characteristic of this condition [3].

Various therapeutic strategies have been explored to manage LPP. Topical treatment remains essential and, in some cases, is combined with oral therapies.

Several isolated cases have shown slight improvement with colchicine or mycophenolate mofetil. Additionally, new therapeutic options are beginning to be explored.

Tranexamic acid is emerging as a promising option in dermatology, although its indications for dermatological disorders remain off-label [9].

Recently, various case reports and clinical trials have highlighted its role in different contexts, including post-inflammatory hyperpigmentation, dermal melanosis, rosacea, telangiectasia, and even as an anti-aging agent [10].

Systemic and intradermal administration of tranexamic acid has proven effective in treating melasma [9], opening the door for its potential use in managing pigmented lichen planus (LPP).

Its effectiveness is based on its beneficial properties in pigmentary disorders, such as reducing UV-induced melanogenesis and its anti-angiogenic action, yet it appears to be dose-dependent [1].

Isotretinoin, due to its anti-inflammatory properties, has also proven effective in treating pigmented lichen planus (LPP), [2] as observed in our patients.

It appears to interrupt the immunological progression and activity of the disease, thereby reducing basal cell damage and the extent of pigmentary incontinence. This mechanism facilitates the rapid elimination of pigments by macrophages [2].

However, data on effective LPP treatments remain highly limited, with most available information coming from case reports and series [11].

To our knowledge, this was the first study in Morocco evaluating the efficacy and tolerance of the combination of oral tranexamic acid and oral retinoids in the treatment of LPP.

In our study, partial improvement was observed in more than 50% of the patients, aligning with results reported in the literature [1].

CONCLUSION

LPP is a prevalent pigmentary disorder with distinctive clinical and histological characteristics. It presents typically as persistent, asymptomatic, slaty-gray pigmentation predominantly on sun-exposed areas such as the face and neck, with lesions often bilaterally symmetrical [12].

Our study suggested that tranexamic acid could be an effective therapeutic option for pigmented lichen planus, with a good safety and tolerance profile [13].

Similarly, low-dose isotretinoin appears to be a promising modality for stabilizing and reducing pigmentation, particularly in early and localized cases of the disease [2].

Despite the small sample size, our results were promising and highlighted the need for larger-scale studies to confirm and further evaluate the efficacy of these systemic treatments for this indication.

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