Photodynamic therapy (PDT) may be a treatment option for patients with uncommon forms of lichen planus (LP), researchers reported in a letter published in Dermatologic Therapy.
Investigators detailed their findings from 2 patients with uncommon forms of hypertrophic and erosive plantar LP that were successfully treated with PDT with use of Aktilite model CL128 (PhotoCure ASA) and methyl aminolevulinate (MAL) 16%. An identical treatment protocol was used for both patients, with a different frequency of sessions in patient 2. The incubation time of MAL was 3 hours, and the fluence was 37 J/cm2 in each session.
Patient 1 was a 69-year-old man with a 20-year history of generalized LP with skin lesions and erosive oral lichen planus. Previous treatment was unsuccessful. He also had a pinkish plaque with a white perifollicular coloration on the dorsum and palm of his right hand. A biopsy revealed hyperkeratosis with parakeratosis, acanthosis, and a band-like lymphohistiocytic infiltrate at the dermo-epidermal junction, as well as a cleft formation between the epidermis and papillary dermis and melanin pigment within macrophages of the dermis. He received clobetasol 0.5 mg/g and intralesional triamcinolone 40 mg/mL, which led to initial improvement but later progression. Red-light PDT with MAL 160 mg/g was initiated after the patient refused oral acitretin. Regional hand anesthesia and curettage were conducted before each session. Complete resolution of the lesion was achieved after 6 sessions (1 per month), and no side effects were reported.
In patient 2, a 42-year-old man presented with scaly and erosive lesions on the plantar feet with psoriasis. He received 6 months of treatment with clobetasol 0.5 mg/g combined with topical tacrolimus 0.1% and acitretin, but the lesions did not improve. A biopsy was consistent with erosive lichen planus. Red-light PDT with MAL 16% was administered every 2 months because the patient lived far away from the hospital. Paracetamol 1 g was administered before every session to try and reduce pain during the process. The patient had a decrease in the affected area and in pain when walking after 6 sessions. He discontinued the treatment due to severe pain during the process, and no other side effects were reported.
PDT is based on the combination of light, oxygen molecules inside the targeted cells, and a photosensitizer agent, and several studies have shown positive results in oral lichen planus, including the erosive form. Narrowband ultraviolet B phototherapy and psoralen plus ultraviolet A phototherapy have been used successfully to treat patients with recalcitrant and disseminated LP, although they require more sessions than PDT, noted the researchers.
“PDT can be considered as a novel treatment option for uncommon and localized forms of recalcitrant LP, due to the lack of side effects, wide availability, and promising results observed in our 2 cases.”
Fernández-Parrado M, Arostegui-Aguilar J, Perandones-González H, Hiltun I, de Dot-Gomara T, Larra-García M. Photodynamic therapy in uncommon forms of lichen planus. Dermatol Ther. Published online October 9, 2022. doi:10.1111/dth.15914