Transcript 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
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Structure of the skin
Common lesions
Premalignant lesions
Melanoma
Boundaries
• Basic structure applicable to SIAgraphs
• Melanoma
• Conditions that can be mistaken for
melanoma
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
Structure of the skin
• Epidermis
• Dermis
Epidermis
Dermal
papillae
Dermis
Rete
ridges
1.2 Histology of the skin
• Epidermis – 5 layers
– Stratum corneum
– Stratum granulosum
• Dermis
– Papillary
– Reticular
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
Dermis + Beyond
• Dermis
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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
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
Histology of skin naevi
• Normal skin
Histology of skin lesions
• Freckles
– Seen on many people
• Junctional naevus
– Common “mole”
Compound naevus
• Acquired between 6 months and 35
years
• May be raised
• Brown
Compound naevus histology
Nests of melanocytes
at rete tips
Nests of melanocytes in dermis
producing less melanin
Compound naevus
Blue Naevus
• Usually begin early in life
• May appear similar to nodular
melanoma
• Rounded nest of melanocytes in the
dermis
• Blue.
Blue Naevus histology
Blue Naevus
Spitz / Spindle Cell Naevus
• Occurs mainly in children
• Smooth, round, slightly
scaling pink nodule
• Very difficult to diagnose
– Resemble melanoma even
in histology.
Spitz / Spindle Cell Naevus
Seborrhoeic Keratosis
• Acquired in middle and later life
• Slow-growing
• Scaling / “stuck-on” appearance
Seborrhoeic Keratosis Histology
Seborrhoeic Keratosis
Pyogenic Granuloma
• Proliferation of blood vessels
Pyogenic granuloma
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
Haemangioma Histology
• Lacunes of blood
Cherry Angioma
Premalignant
• Lentigo maligna
• Dysplastic naevus
Dysplastic Naevus – warning!
• With or without dermal nests
• Capillary proliferation
• Increase in Collagen in dermis
Dysplastic Naevus – warning!
Lentigo Maligna
• Precursor to lentigo maligna melanoma
• Large, cosmetically sensitive areas
• Excision undesirable in frail/elderly
patients unless lesion changes to
lentigo maligna melanoma
Lentigo Maligna
• Punch biopsies sometimes used to
confirm diagnosis
• Disfiguring, inaccurate
• Dermal melanin SIAgraph indicates
change to lentigo maligna melanoma
Lentigo Maligna
Histology of skin lesions
• Melanoma – stages
– Radial Growth Phase (RGP)
– Vertical Growth Phase (VGP)
Histology of Melanoma
Melanoma
• Superficial spreading melanoma (SSM)
• Nodular malignant melanoma (NMM)
• Amelanotic melanoma
Superficial Spreading
Melanoma
• Radial Growth Phase
• Microinvasion
SSM - Histology
Superficial Spreading
melanoma
NMM
• VGP
• Larger areas of dermal melanin
1.2 Histology of skin lesions
Nodular melanoma
Amelanotic Melanoma
• Less melanin
• Very rare
• SIAscope can diagnose in theory
– No amelanotic melanomas in studies as
yet
Amelanotic melanoma
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.
Melanoma Prognosis
• Breslow thickness
– Stratum granulosum to bottom of tumour in mm
• Clark’s level
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5:
in situ (epidermis)
upper papillary dermis
full thickness of papillary dermis
reticular dermis
subcutaneous fat
• Several others
• Breslow thickness
End of presentation
• Many different conditions
may appear clinically
similar to melanoma
• Diagnosis is difficult
– More in the next
presentation