Phototherapy Flashcards
Phototherapy is divided into what two modalities?
UVA (320-400nm) and UVB (280-320)
UVA and UVB wavelenghts:
UVA- 320-400
UVB 280-320
What does PUVA stand for?
Psoralen plus UVA
What is the basic mechanism of PUVA?
photochemical reaction between psoralen (8-methoxypsoralen) and UVA light—> decreased DNA synthesis/cell cycle arrest
note- before UV exposure, the psoralen actually intercalates into DNA
What are some uses for PUVA?
- psoriasis
- vitiligo, CTCL,dermatitis, photodermatoses, GVHD, lichen planus
What are the AE’s of PUVA?
phototoxic reactions (erythema and pruritis)
- NMSC SCC>BCC (if> 250 treatments)
- melanoma
- cataracts
> _____ PUVA treatments increases risk of NMSC.
>250 treatments (SCC>BCC)
What is wavelength of narrow band UVB?
311-313nm
What is the MOA of nbUVB?
decreases DNA synthesis
- increases p53–> cell cycle arrest/keratinocyte apoptosis
- decreases proinflammatory cytokines
- decreases langerhans cells
What is the treatment of choic for vitiligo?
narrow band UVB
What are the uses of nbUVB?
- psoriasis (most commonly prescribed phototherapy for psoriasis)
- mycosis fungoides
- vitiligo (tx of choice!)
- atopic dermatitis
- photodermatoses
- pruritis
Of BB-UVB, nbUVB and PUVA, which has lowest increased risk of NMSC
nbUVB
Which laser has a UVB wavelength and is good for treating small areas of vitiligo or psoriasis? What is the wavelength?
Excimer laser (308nm)
What is the MOA of PDT?
activation of topical photosensitizer by light—> photosensitzers are converted to protoporphyrin IX which accumulates in neoplastic cells more than normal cells
—> necrosis/apoptosis of malignant cells
what are the two topical agents that can be used for PDT and which lights activate them, and what are their wavelengths?
Aminolevulanic acid (ALA)- activated by blue light- 410nm
Methyl aminolevulinate (MAL): activated by red light- 635nm
remember red=evil=”mal” in spanish
