Doctoral dissertation
2021
Katrine Togsverd-bo, MD, Ph.d. Dept. of Dermatology, Copenhagen University Hospital Bispebjerg

Keratinocyte dysplasia in organ transplant recipients: Treatment and prevention with photodynamic therapy and non-invasively measured skin photodamage

Aim of the Thesis

The aim of the thesis was to investigate ablative fractional laser to improve PDT ecacy for AK in OTRs and to evaluate the eect of PDT for primary prevention of AK. Furthermore, we explored associations between non-invasively measured photodamage and KC in OTRs to identify high-risk patients that could benet from prophylactic PDT treatments.

The overall objective of the thesis was assessed in three sections:

I. To assess PDT's ecacy for AK clearance in OTRs, and to investigate the potential of ablative fractional laser in combination with PDT to increase AK clearance. First, we aimed to determine the ecacy of conventional MAL-PDT compared to imiquimod for AK clearance. Second, we attempted to improve the PDT clearance of thin and keratotic AK by combining ablative fractional laser resurfacing prior to conventional and daylight PDT. These points were evaluated in 3 randomized controlled trials in Study I-III.

II. To explore the potential of PDT for primary prevention of AK in renal transplant recipients and for SCC in a hairless mouse model. In renal transplant recipients, we compared split-side conventional PDT treatment for 5 years with no treatment to prevent rst onset of keratinocyte dysplasia in Study IV. In hairless mice, we explored the potential of repeated, articial daylight PDT with low photosensitizers concentrations to prevent SCC in Study V.

III. To investigate the potential of non-invasive, objective measurements to determine skin photodamage in OTRs and immunocompetent patients with skin cancer. We assessed associations between KC and UVR exposure and objectively measured photodamage in terms of skin pigmentation, skin autouorescence, and black-light evaluated solar lentigines in Study VI. Furthermore, we explored dierences in non-invasively measured photodamage adjacent to KC in OTRs and immunocompetent patients with KC in Study VII.

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