PHOTODERMATOSES Flashcards
• Young adults in spring, early summer
• Attacks are intermittent and occur minutes to hrs after UV exposure
• Morphology:
– nonscarring pruritic erythematous papules and papulovesicles or
plaques on some or all of the uncovered skin
• UVA through car windows can trigger PMLE
• Characteristic path feature: papillary dermal edema with perivascular
lymphocytes
what is this photodermatoses?
Polymorphous Light Eruption
• Papular/nodular, pruritic, excoriated eruption
• Think Native American children
• Ddx: porphyrias, prurigo nodularis, varicella
• Tx: Topical steroids, topical calcineurin inhibitors, hardening
therapy, thalidomide
what is this photodermatoses?
Actinic Prurigo
• Rare photosensitive bullous dermatosis
• Episodic (like PMLE)
• Usually begins in childhood
• M > F
• Morphology
– Symmetrical clustered pruritic red macules of exposed sites, especially face and dorsal aspects of hands
• Appears within hours of sunlight exposure
• Possible association with EBV & rarely lymphoma
• Tx - sun protection, topicals, cyclosporine, azathioprine, thalidomide
what is this photodermatoses?
Hydroa Vacciniforme
• Aka actinic reticuloid/photosensitivity dermatitis
• UVR and occasionally visible light sensitive eczema
• Represents what sort of hypersensitivity, against what?
– DTH (IV) response against photoinduced endogenous antigen
• T/F: any skin color is susceptible
– True
what is this photodermatoses?
Chronic Actinic Dermatitis (CAD)
• Transient cutaneous whealing immediately following UVR or
visible light exposure; last less than 24 hours
• As with other forms of urticaria, mast cell mediated
• Involves an immediate response to photo-induced allergen
• 2nd - 3rd decade
• Can be associated with nausea, lightheadedness
• Has been reported to be induced with tetracyclines
• Repeated exposure → diminished symptoms (hardening)
• PMLE lasts longer (days) and occurs later (hours-days)
what is this photodermatoses?
Solar Urticaria (SU)
• Heritable AR defect in nucleotide excision repair genes (XPA-XPG)
• Very early development of sun damage (lentigines, ephelids, erythema,
poikiloderma)
• 1000-fold increased risk of skin cancer (avg age of 1st cutaneous
malignancy is 8 yo)
• Ophthalmic and neurodevelopmental complications
• Lifespan shortened 2/2 invasive melnoma or inv SCC
• Topical endonucleases (T4N5) and systemic retinoids decrease ca risk
what is this photodermatoses?
Xeroderma Pigmentosum
• AR defect in ERRC6 or ERCC8 → transcription-coupled nucleotide excision
repair (vs XP which is global genomic NER defect)
• Very early photosensitivity, but NO increased risk of skin cancer and NO
pigmentary changes
• Pinched bird-like facies with beaked nose, sunken eyes, growth failure,
cachectic dwarfism
• Progressive basal ganglia calcification → neurodegeneration (cause of death)
• Salt & pepper retinopathy
• XP-CS overlap syndrome - stigmata of both
what is this photodermatoses?
Cockayne Syndrome
AR group of disorders, some of which have overlap with XP (photosensitivity) because they are allelic with XPB (ERCC3), XPD (ERCC2), but no increased risk of skin cancer. Brittle hair, ID, immunodef.
what is this photodermatoses?
Trichothiodystrophy
AR BLM/RECQL3 (DNA helicase) causes chromosomal instability & sister-chromatid exchange. Ft: short stature, photosensitivity, malar erythema, bird-like nose, hypogonadism, immunodef., leukemia
what is this photodermatoses?
Bloom syndrome
AR RECQL4 (DNA helicase). Ft: blistering on cheeks & extensor surfaces, poikiloderma, acral keratoses that may become SCC, alopecia, dystrophic nails, hypoplastic thumbs, osteosarcoma
what is this photodermatoses?
Rothmund-Thompson syndrome
AR RECQL2 (DNA helicase). Ft. Premature grey hair, acral sclerodermatous changes, malignancy (sarcomas, skin ca), atherosclerosis
what is this photodermatoses?
Werner syndrome
