Indoor Daylight Photodynamic Therapy for Actinic Keratosis of the Scalp - Intrapatient Comparison Study - 1 h versus 2 h Exposure Time

Sep 23, 2026

Indoor daylight photodynamic therapy (idl-PDT) is an effective first-line option for actinic keratosis (AK) and field cancerization, but indoor protocols can be limited by long illumination time. This intrapatient comparative study evaluated idl-PDT efficacy and tolerability for scalp AK using 1 h versus 2 h exposure, with methyl aminolevulinate (MAL) and a polychromatic white LED source. Fifty-five patients completed follow-up at 3 and 6 months, with comparable clearance, low pain and reaction scores, and high physician and patient satisfaction.

LanguageEnglish

CategoryHealthcare

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Pages12

Reading Time30 min

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Abstract

Key Summary Points

Why carry out this study?

What was learned from the study?

Introduction

Photodynamic therapy (PDT)

Dermatol Ther (Heidelb) (2026) 16:1113–1124 [https://doi.org/10.1007/s13555-025-01567-z](https://doi.org/10.1007/s13555-025-01567-z) ORIGINAL RESEARCH Indoor Daylight Photodynamic Therapy for Actinic Keratosis of the Scalp: Intrapatient Comparison Study of 1 h versus 2 h Exposure Time Paolo Antonetti · Mariachiara Arisi · Cristina Pellegrini · Grazia Linda Artelli · Alice Zola · Manfredo Bruni · Carola Romanò · Benedetta Galli · Maria Esposito · Piergiacomo Calzavara‑Pinton · Maria Concetta Fargnoli Received: July 19, 2025 / Accepted: October 3, 2025 / Published online: December 30, 2025 © The Author(s) 2025 ABSTRACT Introduction: Several treatments are avail‑ able for actinic keratosis (AK), many of which are hampered by local inflammation, pain, long duration, and slow healing. Indoor daylight photodynamic therapy (idl‑PDT) is an effec‑ tive, well‑tolerated, first‑line treatment for both AK and field cancerization, but its feasibility is Prior Presentation: The results of this study were previously presented by Dr. Paolo Antonetti as a poster atthe 21st EADO Congress (Athens, 3–5 April 2025), poster number A‑610, and at the XIV International Congress of Dermatology (Rome, 18–21 June 2025), poster number 1854, and by Prof. Maria Concetta Fargnoli atthe 22nd Annual Congress of the European Society for Photodynamic Therapy (Brussels, 30–31 May 2025) . P. Antonetti · M. Bruni · M. Esposito Dermatology Department, San Salvatore Hospital, L’Aquila, Italy M. Arisi · G. L. Artelli · C. Romanò · B. Galli · P. Calzavara‑Pinton Dermatology Department, ASST Spedali Civili di Brescia, University of Brescia, Brescia, Italy C. Pellegrini (*) · A. Zola · M. Bruni · M. Esposito Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, Coppito 2, Via Vetoio, 67100 L’Aquila, Italy e‑mail: [cristina.pellegrini@univaq.it](cristina.pellegrini@univaq.it) M. C. Fargnoli San Gallicano Dermatological Institute, IRCCS, Rome, Italy limited by the long time required for illumina‑ tion (2 h) . The objective of our study was to evaluate the efficacy of idl‑PDT with an illumi‑ nation time of 1 h versus 2 h in the treatment of scalp AK. Methods: We conducted an intrapatient, com‑ parative study of idl‑PDT with two illumination durations, 1 h versus 2 h, using methyl ami‑ nolevulinate (MAL, Metvix®) and a white light‑ emitting diode (LED) light (Dermaris®) for the treatment of scalp AK. Patients were evaluated 3 months and 6 months after one session of idl‑ MAL‑PDT for AK response rate, both overall and by AK grade, and tolerability. Physicians’ and patients’ satisfaction were also investigated. Results: A total of 55 patients were enrolled with a total of 955 AK (grade I–II) . The AK clear‑ ance rate was 72.9% in 1 h‑half and 71. 1% in 2 h‑half after 3 months, and 76.2% in 1 h‑half and 78.9% in 2 h‑half after 6 months. No statis‑ tically significant difference in efficacy (overall, grade I and II AK) was observed between the two illumination times, both at 3 and 6 months. The local skin reaction score and pain numeric rat‑ ing scale (NRS) were very low, and comparable between the two treatment arms. Both physi‑ cians and patients expressed very good opinion on effectiveness and cosmetic outcome. Overall, 96.4% of patients would undergo idl‑PDT again. Conclusions: The efficacy of idl‑PDT in treat‑ ing grade I and II AK of the scalp was compara‑ ble using 1 h or 2 h as illumination time. Both treatment schedules were well tolerated, with avery high rate of satisfaction from both physi‑ cians and patients. This trial was retrospectively registered on the 4th of December 2025. Trial registration: Clini‑ calTrials. gov identifier, NCT07290959 . Keywords: Actinic keratosis; Field cancerization; Idl‑PDT; Indoor daylight photodynamic therapy; MAL‑PDT; Methyl aminolevulinate; PDT; Photodynamic therapy Key Summary Points Why carry out this study? This study was conducted to explore an alterna

FAQs

What was the main objective of this intrapatient study?

To compare the efficacy and tolerability of indoor daylight photodynamic therapy (idl-PDT) for scalp actinic keratosis using 1 hour versus 2 hours of illumination time.

How were patients treated in the study?

Patients received idl-MAL-PDT for scalp AK using methyl aminolevulinate (MAL, Metvix®) and a white light-emitting diode (LED) source (Dermaris®), with two illumination durations: 1 h and 2 h.

What were the efficacy and tolerability findings at 3 and 6 months?

AK clearance rates were similar between 1 h and 2 h at both 3 months and 6 months, with no statistically significant differences. Local skin reaction scores and pain numeric rating scale (NRS) were very low and comparable between arms, and satisfaction was very high.

Sep 23, 2026

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