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Photosensitivity and Skin Cancer. Dermatology BM2023 Dr Tim Scott-Taylor Health and Human Sciences. Topics. Revision of structure & function of epidermis Effects of irritants and insults on skin Pathological effects of ultraviolet on skin Kinds of skin tumours; benign lesions
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Photosensitivity and Skin Cancer Dermatology BM2023 Dr Tim Scott-Taylor Health and Human Sciences
Topics • Revision of structure & function of epidermis • Effects of irritants and insults on skin • Pathological effects of ultraviolet on skin • Kinds of skin tumours; benign lesions basal cell carcinoma squamous carcinoma melanoma
Learning Objectives • to review normal structure & function • to know how skin adapts to insults • to visualise the consequences of the failure of skin to adapt • to identify the range of skin responses to sunlight • to know the varieties and outcomes of the different kinds of skin cancer
Epidermis Squamous, multilaminate Keratin and fatty acid deposition Melanin uptake Intercellular bridges
Epidermal Layer Functions • Stratum corneum (keratin): tough, flexible, waterproof • Basal keratinocytes: mitotically active; susceptible to UV • Melanocytes: pass melanin to suprabasal keratinocytes • Langerhans cells: immune communication • Basement membrane: cements epidermis to dermis
Dermal Layer Functions Enervation of skin by Merkel cells in the stratum basale free nerve endings (Rafini) Pacinian corpuscles Temperature regulation by control of dermal and subcutaneous capillary blood flow
Skin Diseases More known diseases than any other organ; • You can see the skin • You can examine and biopsy the skin • The skin interfaces more with the environment • One skin disease leads to another; rash – scratch – excoriation – dermatitis • Seldom life threatening; often disfiguring
Epidermal Adaptation • Stratum corneum;hyperkeratosis thickening with trauma • Epidermis; lichenificationthickening with scratching • Dermoepidermal junction: blisters with trauma • Melanocytes: tanning with UV exposure
Hypertrophy LICHENIFICATION
Lichenification Thickening of the stratum cornium accentuated skinfolds or creases that appear as deep grooves and wrinkles. Itching Atopic dermatitis scabies
Skin Adaptation 2 Hyperkeratosis Solar keratosis Corns and bunions Increased deposition of keratin in epidermal cells Abrasion, repeated trauma, chronic sun exposure
Skin Adaptation 3 Blistering Oedema between dermal and epidermal layers Sloughing of epidermis Replacement of epidermis Elimination of infectious and toxic agents
Epidermal Dysfunction • normal structure & function • skin adapts to insults • vital role is illustrated by skin failure
Pemphigus Immune reaction to skin Antibody deposition at epidermal/dermal junction Influx of cytotoxic lymphocytes Sloughing of epidermis
Burns Slow and flawed epidermal replacement Integrity of Stratum basale compromised Permanent scarring Loss of thermoregulation sweating and sensitivity
Erythroderma generalized dilation of cutaneous blood vessels Reddening and thickening of epithelium Loss of epidermis severe psoriasis, atopic dermatitis, drug eruptions, Sezary syndrome (T-cell lymphoma) Life threatening or disfuguring
Skin Failure Skin function illustrated toxic epidermal necrolysis by epidermal dysfunction; severe pemphigus erythroderma burns Staphylococcal Scalded Skin Syndrome • Dehydration/shock • Infection/septicaemia • Hypothermia, • protein loss • high-output cardiac failure Loss of >33% of epidermis can be fatal without thermal homeostasis and infection control
Skin Adaptation 4 Melanocytes; sporadic inclusion in stratum basale Melanisation of epidermal keratinocytes
UV Penetration of Skin Less than 10% of UVA or UVB reaches the dermis
Melanin Lowers Cancer Risk INCIDENCE OF Skin Cancer 1 in 100 to 200 1 in 2,000 to 5,000 1 in 5,000 to 10,000
Solar Radiation Various wavelengths from 50 to 5000 nm Low frequency high energy ionising associated with genetic mutations
Utraviolet Light • Long wave (UVA) 320-400nm ‘black light’, tanning beds, can burn, partly carcinogenic • Medium wave (UVB) 290-320 nm sunburn, vitamin D, strongly carcinogenic, photoaging • Short wave (UVC) 200-290nm nucleic acid damage (260nm), little in sunlight
retenoic acid trentinoin Sunburn cc to tt double base subsitution biopsy of sunburn; apoptotic cells, p53 directed oedema hyperaemia chronic UV; photoaging wheather beaten changes to dermal ground substance deep furrowing collagen type 1 loss metaloprotease Solar elastosis Solar keratosis
Solar Elastosis dermal solar elastosis patchy sun-related damage in the dermis hyperplasia of dermal fibroblasts deposition of elastin and collagen
Solar Elastosis damaged collagen resembles barbed wire due to damage to the elastin by the sun
Actinic Keratosis red, rough, scaling spots sun-exposed areas; face, ear, balding scalp, hand, forearm cumulative skin damage repeated exposure to UV irreparable damage to epidermis precancerous
Photoaging Epidermis thins Becomes shiny and wrinkles Loses elasticity Atrophies Appearance of minor pigmented lesions; lentigines cherry angiomas seborrheic keratosis
Spots freckles = ephilides close linkage with red hair and melanocortin receptor solar lentigines liver spots age spots hyperplasia of melanocytes harmless
Topics Kinds of skin tumours; benign lesions basal cell carcinoma squamous carcinoma Karposi’s sarcoma melanoma recognition and diagnosis cellular changes treatment
Learning Objectives • to recognise the appearance of the common varieties of skin cancer • to know the outcomes of the different kinds of skin cancer
Skin Cancers More common than other kinds of cancer sun exposed skin, mostly of outdoor workers, sunbathers 75,000 new cases registered per year UK registration incomplete, >100,000/yr? 70-80 % Basal cell carcinoma 15-20% Squamous cell carcinoma Melanoma <4% Karposi’s sarcoma cutaneous T cell L
Skin Biopsy Suspicious lesions should be biopsyied and examined by cytology Punch biopsy under local anaesthetic
Lesion Basal cell carcinoma Incid. ~75% of skin cancers Age Usually 40+ Sex Male > Female Causes Sunlight, arsenic, X-ray, trauma, burn scar Location Nodular - Head/NeckSuperficial - TrunkMorphea - Face Lesion Transluscent papule, Telangictasias, pigment in dark skinRed - macule on plaqueYellow, white indunated maqule in plaque Symptoms Cosmetically objectionable.Ulcerates and bleeds Rx < 1 CM 95% EFFECTIVE< 1 CM EXCISON OR RADIATION Course ED&C 95% effectiveRare metasteses about 17% Basal Cell Carcinoma
Basal Cell Carcinoma Several different morphologies 1. Red scaly papule Translucent, shiny, firm Difficult to distinguish from solar keratosis Indurated, may ulcerate Metastasis rare but local invasion disfiguring
Basal Cell Carcinoma Often appears as an eroding papule that wont go away Often ignored or misdiagnosed highly treatable survival rates >95%
Basal Cell Carcinoma • Occurs in area of previous skin damage
Cells resemble basal cell epithelia Regular array and columnar shape Basal Cell Carcinoma
Bowen’s Disease red-brown, scaly, crusted, little induration resembles localized thin plaque of psoriasis, dermatitis, or a dermatophyte infection Local non-penetrative squamous carcinoma treatment by curettage, electrodesiccation, excision, or cryosurgery
Squamous Carcinoma malignant tumor of epidermal keratinocytes that frequently invades the dermis Typically an eroding ulcer with a raised edge Most frequently on back of hands or face
Squamous Carcinoma Highly invasive destructive Likely to metastesise 34% 5yr survival after metastasis
Squamous Cell Carcinoma Typically shows whorls and pearls
Karposi’s Sarcoma Multicentric vascular tumour Caused by HHV8 infection of endothelial cells Occurs in endemic AIDS-associated and post-transplant forms Treatment by cryotherapy, electrocoagulation and radiotherapy
AIDS-Associated Karposi’s Endemic form in Africa without AIDS, prepubertal Imunosuppressive KS developes years after organ transplant Epidemic KS, most common AIDS associated malignancy Multiple cutaneous lesions, usually on face or trunk, pink/purple macules that coalesce to nodules Lymph node and GI tract involvement Fulminant and fatal