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Dermatology
Photodynamic Therapy
Built from Dermatology, 5th Edition
What’s inside
8 sections · 92 slides
Overview
- What photodynamic therapy is
History and Development
From a dye that only killed cells in light, to a skin cream activated by the sun
- Early discovery of the photodynamic effect
- Modern era: systemic photodynamic therapy
- The breakthrough: topical ALA
- FDA approvals and the rise of daylight PDT
Mechanism of Action
Photochemistry, photobiology, and why PDT stays selective for diseased skin
- PDT compared with PUVA therapy
- Photodynamic therapy versus PUVA therapy
- Photosensitizer delivery and photodynamic cell injury
- PDT photochemistry: from light to singlet oxygen
- Jablonski energy-state diagram of photoactivation
- Why light color (wavelength) matters
- Absorption spectrum of protoporphyrin IX
- Fluorescence and photobleaching
- Fluorescence of tumor PpIX before and after light exposure
- How PDT kills cells: two main pathways
- Dose intensity and type of tissue injury
- Immune and antimicrobial effects
- PDT selectivity: why treatment stays targeted
- What keeps PDT selective for the lesion
- Therapeutic selectivity during photodynamic therapy
- Fluorescence of a superficial basal cell carcinoma under Wood's lamp
- Advantages of PDT
- Limitations of PDT
Components of PDT
The photosensitizers, light sources, and dosing math behind every treatment
- Photosensitizers used in dermatology
- Chemical structures of ALA, methyl aminolevulinate, and PpIX
- How ALA gets into skin cells
- ALA and mALA formulations
- Newer photosensitizer formats
- Choosing a light source: three considerations
- Artificial (conventional) light sources
- Daylight-activated PDT (D-PDT)
- Practical rules for daylight PDT
- Comparison of PDT techniques: artificial light-activated PDT
- Comparison of PDT techniques: daylight-activated PDT (D-PDT)
- Comparison of PDT techniques: alternative technique variations (off-label)
- Comparison of PDT techniques: alternative technique variations (off-label) (continued)
- Measuring the PDT light dose
- Dosimetry: balancing drug and light
- Fractionating the light dose
- Incubation time and drug buildup
Dermatologic Applications
From FDA-approved skin cancer indications to a growing list of off-label uses
- Overview of PDT uses in skin disease
- The two broad families of PDT use
- Photodynamic therapy - dermatologic applications
- Oncologic use: general principles
- Actinic keratoses: how well PDT works
- Facial actinic keratoses and photoaging before and after PDT
- Actinic keratoses on hands and arms
- Actinic keratoses in transplant recipients
- Daylight PDT for actinic keratoses
- Facial actinic keratoses before and after daylight PDT
- Actinic cheilitis
- Superficial basal cell carcinoma: outcomes
- Large superficial basal cell carcinoma before and after PDT
- When PDT is not the right choice for BCC
- PDT for multiple BCCs and daylight BCC treatment
- Superficial basal cell carcinoma two years after PDT
- Squamous cell carcinoma in situ (Bowen disease)
- Bowen disease on the lower leg
- Using PDT to prevent skin cancer
- Extramammary Paget disease and other rare uses
- PDT for T-cell lymphoma and historic uses
- Acne: how and why PDT helps
- Photodynamic therapy for recalcitrant acne vulgaris
- Blue light alone and other acneiform disorders
- Photoaging
- Cutaneous infections
- Vascular birthmarks
Adverse Effects and Complications
Pain, photosensitivity, and inflammation are expected parts of how PDT works
- Why PDT causes side effects
- Photosensitivity reactions
- Pain during light exposure
- Reducing PDT pain
- Skin reaction four days after photodynamic therapy
- Local inflammation after treatment
- Allergy to the photosensitizer
- Rare and unusual reactions
Practice and Techniques
What actually happens before, during, and after a PDT session
- Planning a PDT session
- The four phases of a PDT visit
- Steps in administering topical PDT and practical considerations
- Steps in administering topical PDT and practical considerations (continued)
Future Directions
New drugs, gentler light, and PDT paired with non-invasive imaging
- What's next for PDT
- 90%
- Summary
- References
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- Dermatology, 5th Edition (2-Volume Set)