Efficacy of narrowband phototherapy in the treatment of different forms of psoriasis with the predominant affection of palms and soles

Background: Palmar-plantar psoriasis is characterized by a torpid course and resistance to conventional systemic treatments. Phototherapy is usually considered as an adjuvant treatment of a patient with psoriasis. The potential use of phototherapy as a basic treatment strategy in limited psoriasis, including its plantar-palmar localization, could be of interest. Aim: To study the efficacy, safety and tolerability of the narrowband phototherapy (UVB 311 nm) in the treatment of different forms of psoriasis with predominant palmar-plantar involvement. Materials and methods: We retrospectively analyzed the results of treatment of 77 in-patients admitted to the Department of Dermatology for treatment of various types of psoriasis with prevailing palmar and plantar lesions. The main group consisted of 42 patients who were administered combination therapy including topical corticosteroids, hepatic protectors, antihistaminic agents and, in addition, the narrowband phototherapy with a phototherapy device Dermalight 500-1 (Dr. Hnle Medizintechnik GmbH, Germany). The initial radiation doses were set without the determination of the minimal erythema dose, depending on the patient's skin type, in accordance with the guidelines from the manufacturer. At each consecutive session, the dose was increased by 0.060.3 J/cm. The sessions were conducted 5 times a week with a total of 1421 sessions. The mean cumulative dose was 22.8 J/cm. The control group included 35 age-, gender- and psoriasis severity-matched patients who received the same treatments, except the narrowband phototherapy. The treatment efficacy was assessed by changes in the Palmoplantar Pustulosis Area and Severity Index (PPPASI). Clinical results of treatment were evaluated at day 10 after the treatment course had been completed. Results: No serious adverse events were registered during the treatment. In the patients with psoriasis vulgaris and predominant palmoplantar lesions, receiving the narrowband phototherapy, the PPPASI reduction was higher than in the patients who received only conventional treatment (U-test, p = 0.015). A PPPASI decrease of 50% was observed in 83.3% (25/30) and 60% (15/25) of the patients, respectively. Clinical efficacy criteria were achieved in 66.6% (8/12) of the patients with palmoplantar pustular psoriasis receiving the combination treatment with phototherapy and in 40% (4/10) of the conventionally treated patients in the control group; however, the difference in the distribution of remission achievement was non-significant (U-test, p = 0.123). Conclusion: The study has demonstrated the efficacy of UVB 311 nm narrowband phototherapy in the treatment of patients with psoriasis with predominant palmoplantar lesions. The results obtained make it possible to recommend the inclusion of the narrowband phototherapy UVB 311 nm at mean cumulative dose of 22.8 J/cm into the standardized set of treatments of patients with psoriasis vulgaris with predominant palmoplantar lesions, not only as an adjuvant technique, but also as the main therapeutic strategy. The role of the narrowband phototherapy UVB 311 nm in the treatment of palmoplantar pustular psoriasis, as well as the dosing regimens of the radiation and determination of the necessary follow-up duration should be the subject of further studies.