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SIAscope Training Course

SIAscope Training Course. Micro-architecture of skin lesions. SIAscope training course aims. After this course you will be able to discuss: Common skin lesions, and their histology Methods of melanoma diagnosis and their relative merits. Programme. Structure of the skin Common lesions

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SIAscope Training Course

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  1. SIAscope Training Course Micro-architecture of skin lesions

  2. SIAscope training course aims • After this course you will be able to discuss: • Common skin lesions, and their histology • Methods of melanoma diagnosis and their relative merits

  3. Programme • Structure of the skin • Common lesions • Premalignant lesions • Melanoma

  4. Boundaries • Basic structure applicable to SIAgraphs • Melanoma • Conditions that can be mistaken for melanoma

  5. Motivation • 18% of melanomas are misdiagnosed in first clinical episode – BJD 1999 • Difficulties of diagnosis • Skin is a complex organ • Many components • Components may have strong visual resemblance to each other • Different conditions can look the same

  6. Structure of the skin • Epidermis • Dermis

  7. Epidermis Dermal papillae Rete ridges Dermis

  8. 1.2 Histology of the skin • Epidermis – 5 layers • Stratum corneum • Stratum granulosum • Dermis • Papillary • Reticular

  9. Epidermis • Stratum Corneum (Hornlike Layer) • 20-30 layers of dead, anucleated cells • outer cells are constantly shed • Stratum Lucidum (Clear Layer) • only seen in thick skin • 2-3 layers of dead, anucleate cells • Stratum Granulosum (Granular Layer) • 3-5 layers of granular, flattened cells • Stratum Spinosum (Spiny Layer, Prickly Layer) • several layers of polygonal-shaped cells • Stratum Basale (Basal Layer) • single layer of columnar/cuboidal cells resting on basement membrane

  10. Dermis + Beyond • Dermis • Separates into papillary and reticular dermis • Dense irregular connective tissue –Collagen • Contains nerve endings, hair follicles, glands, capillaries • Dermal papillae (projections of dermal tissue into the epidermis) interlock with rete ridges • Hypodermis or Superficial Fascia • Subcutaneous tissue underneath dermis • Stores fat and helps anchor skin

  11. Common lesions • May appear similar to melanoma • But benign • Appearance and history important • Junctional, Compound, Intradermal naevi • Blue, Spindle-cell naevi • Seborrheic Keratosis • Pyogenic Granuloma • Haemangioma

  12. Histology of skin naevi • Normal skin

  13. Histology of skin lesions • Freckles • Seen on many people • Junctional naevus • Common “mole”

  14. Compound naevus • Acquired between 6 months and 35 years • May be raised • Brown

  15. Compound naevus histology Nests of melanocytes at rete tips Nests of melanocytes in dermis producing less melanin

  16. Compound naevus

  17. Blue Naevus • Usually begin early in life • May appear similar to nodular melanoma • Rounded nest of melanocytes in the dermis • Blue.

  18. Blue Naevus histology

  19. Blue Naevus

  20. Spitz / Spindle Cell Naevus • Occurs mainly in children • Smooth, round, slightly scaling pink nodule • Very difficult to diagnose • Resemble melanoma even in histology.

  21. Spitz / Spindle Cell Naevus

  22. Seborrhoeic Keratosis • Acquired in middle and later life • Slow-growing • Scaling / “stuck-on” appearance

  23. Seborrhoeic Keratosis - Histology

  24. Seborrhoeic Keratosis

  25. Pyogenic Granuloma • Proliferation of blood vessels

  26. Pyogenic granuloma

  27. Haemangioma • Several kinds • Cherry angioma can be mistaken for melanoma • 2 to 5mm • Red to purple in colour • Usually on the trunk, can be multiple

  28. Haemangioma Histology • Lacunes of blood

  29. Cherry Angioma

  30. Premalignant • Lentigo maligna • Dysplastic naevus

  31. Dysplastic Naevus – warning! • With or without dermal nests • Capillary proliferation • Increase in Collagen in dermis

  32. Dysplastic Naevus – warning!

  33. Lentigo Maligna • Precursor to lentigo maligna melanoma • Large, cosmetically sensitive areas • Excision undesirable in frail/elderly patients unless lesion changes to lentigo maligna melanoma

  34. Lentigo Maligna • Punch biopsies sometimes used to confirm diagnosis • Disfiguring, inaccurate • Dermal melanin SIAgraph indicates change to lentigo maligna melanoma

  35. Lentigo Maligna

  36. Histology of skin lesions • Melanoma – stages • Radial Growth Phase (RGP) • Vertical Growth Phase (VGP)

  37. Histology of Melanoma

  38. Melanoma • Superficial spreading melanoma (SSM) • Nodular malignant melanoma (NMM) • Amelanotic melanoma

  39. Superficial Spreading Melanoma • Radial Growth Phase • Microinvasion

  40. SSM - Histology

  41. Superficial Spreading melanoma

  42. NMM • VGP • Larger areas of dermal melanin

  43. 1.2 Histology of skin lesions

  44. Nodular melanoma

  45. Amelanotic Melanoma • Less melanin • Very rare • SIAscope can diagnose in theory • No amelanotic melanomas in studies as yet

  46. Amelanotic melanoma

  47. Melanoma treatment • Excision to fascia • Margin based on thickness of tumour • Up to 3cm for thick lesions • Sentinel node biopsy(?) • Chemotherapy, Radiation, Immunotherapy (interferon), Medical trials.

  48. Melanoma Prognosis • Breslow thickness • Stratum granulosum to bottom of tumour in mm • Clark’s level • 1: in situ (epidermis) • 2: upper papillary dermis • 3: full thickness of papillary dermis • 4: reticular dermis • 5: subcutaneous fat • Several others

  49. Breslow thickness

  50. End of presentation • Many different conditions may appear clinically similar to melanoma • Diagnosis is difficult • More in the next presentation

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