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Photosensitivity and Skin Cancer PowerPoint Presentation
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Photosensitivity and Skin Cancer

Photosensitivity and Skin Cancer

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Photosensitivity and Skin Cancer

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  1. Photosensitivity and Skin Cancer Dermatology BM2023 Dr Tim Scott-Taylor Health and Human Sciences

  2. 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

  3. 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

  4. Epidermis Squamous, multilaminate Keratin and fatty acid deposition Melanin uptake Intercellular bridges

  5. 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

  6. 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

  7. 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

  8. Skin Insults

  9. Epidermal Adaptation • Stratum corneum;hyperkeratosis thickening with trauma • Epidermis; lichenificationthickening with scratching • Dermoepidermal junction: blisters with trauma • Melanocytes: tanning with UV exposure

  10. Hypertrophy LICHENIFICATION

  11. Lichenification Thickening of the stratum cornium accentuated skinfolds or creases that appear as deep grooves and wrinkles. Itching Atopic dermatitis scabies

  12. Skin Adaptation 2 Hyperkeratosis Solar keratosis Corns and bunions Increased deposition of keratin in epidermal cells Abrasion, repeated trauma, chronic sun exposure

  13. Skin Adaptation 3 Blistering Oedema between dermal and epidermal layers Sloughing of epidermis Replacement of epidermis Elimination of infectious and toxic agents

  14. Epidermal Dysfunction • normal structure & function • skin adapts to insults • vital role is illustrated by skin failure

  15. Toxic Epidermal Necrolysis

  16. Pemphigus Immune reaction to skin Antibody deposition at epidermal/dermal junction Influx of cytotoxic lymphocytes Sloughing of epidermis

  17. Burns Slow and flawed epidermal replacement Integrity of Stratum basale compromised Permanent scarring Loss of thermoregulation sweating and sensitivity

  18. Staphylococcal Scalded Skin Syndrome

  19. 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

  20. 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

  21. Skin Adaptation 4 Melanocytes; sporadic inclusion in stratum basale Melanisation of epidermal keratinocytes

  22. UV Penetration of Skin Less than 10% of UVA or UVB reaches the dermis

  23. 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

  24. Solar Radiation Various wavelengths from 50 to 5000 nm Low frequency high energy ionising associated with genetic mutations

  25. 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

  26. UV Exposure

  27. 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

  28. Chronic UV Exposure

  29. Solar Elastosis dermal solar elastosis patchy sun-related damage in the dermis hyperplasia of dermal fibroblasts deposition of elastin and collagen

  30. Solar Elastosis damaged collagen resembles barbed wire due to damage to the elastin by the sun

  31. 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

  32. Photoaging Epidermis thins Becomes shiny and wrinkles Loses elasticity Atrophies Appearance of minor pigmented lesions; lentigines cherry angiomas seborrheic keratosis

  33. Spots freckles = ephilides close linkage with red hair and melanocortin receptor solar lentigines liver spots age spots hyperplasia of melanocytes harmless


  35. Topics Kinds of skin tumours; benign lesions basal cell carcinoma squamous carcinoma Karposi’s sarcoma melanoma recognition and diagnosis cellular changes treatment

  36. Learning Objectives • to recognise the appearance of the common varieties of skin cancer • to know the outcomes of the different kinds of skin cancer

  37. 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

  38. Skin Biopsy Suspicious lesions should be biopsyied and examined by cytology Punch biopsy under local anaesthetic

  39. 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

  40. 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

  41. Basal Cell Carcinoma Often appears as an eroding papule that wont go away Often ignored or misdiagnosed highly treatable survival rates >95%

  42. Basal Cell Carcinoma • Occurs in area of previous skin damage

  43. Cells resemble basal cell epithelia Regular array and columnar shape Basal Cell Carcinoma

  44. 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

  45. 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

  46. Squamous Carcinoma Highly invasive destructive Likely to metastesise 34% 5yr survival after metastasis

  47. Squamous Cell Carcinoma Typically shows whorls and pearls

  48. 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

  49. 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