Sun Damaged Skin

Sun Damaged Skin

·        Photo-damage = Dermatoheliosis

·        Damage results in:

o  Wrinkling

o  Pigmented lesions

o  Sebaceous hyperplasia (?sun damage or age) 

o  Telangiectasia and purpura (thinned epidermis due to ¯basal cells + flattening out of dermo-epidermal junction ® shearing forces rupture capillaries ® bruising 

o  Pseudoscars

o  Benign and malignant growths

o  Skin laxity

o  Diffusely thickened skin with yellowish micropapular appearance (especially temples), etc, etc

·        Damage relates to life-time dose of UV:

o  Melanoma risk determined by age 15 

o  After that, ¯sun only affects BCC and SCC risk

Sunscreens

·        UVA blockers: block in range 320 – 360 nm. Doesn‟t cause sunburn but is implicated in skin cancer as its harder to filter out

·        UVB blockers: block UV in the range 290 – 320 nm, the sunburn range, but easily filtered. SPF refers to ability to block UVB – not UVA Þ need broad spectrum

·        Types of sunscreen:

o  Cinnamates: UVB

o  PABA: UVB (not commonly used – allergies)

o  Salicylates: UVB

o  Benzophenones: UVA

o  Camphor: UVA

o  Dibenzoylmethane: UVA (good to have in addition to a high SPF)

·        Can use reflective agents (eg titanium dioxide) in addition to absorbers

·        Need behaviour change as well as sunscreen

Lesions

·        Solar Keratosis: See Topic Premalignant Lesions

·        Cutaneous Horn: horny outgrowth, arising from a Solar Keratosis, SCC or seborrheic keratosis. Treat according to underlying lesion

·        Disseminated Superficial Actinic Porokeratosis: Caucasian. Autosomal dominant. First noticed in 40s. Up to 1 cm, slightly red/hyperpigmented on lower leg or forearms. Border has 2 parallel rows of scale

·        Bowen‟s Disease: See Topic Premalignant Lesions

·        Chondrodermatitis: On sun damaged ears, may also be due to pressure. Commonly on helix of pinna. Painful when pressed. Differential SCC (usually large and not as painful) or BCC (pearly, not often on rim of ear). Treatment: excision including cartilage otherwise recurrence

·        Lentigo: Brown macules (look like large freckles). Solitary, multiple or generalised. May be part of a syndrome. In adults they are usually sun induced, on back of hand or back. Can get a solitary dark one

·        on the lower lip after sunburn. Differential of dark ones: melanoma. May require excision to differentiate

·        Idiopathic Guttate hypomelanosis: pale spots in the shape and distribution of largish freckles on sun damaged skin

·        Freckle: brown macule. Due to ­ pigment production but anatomically normal. Fades if sun exposure ceases. Commoner in redheads