Skin I (b) Flashcards
patho of Seborrhoeic Keratosis
Mutations in fibroblast growth factor (FGF) receptor 3
Epi of Seborrhoeic Keratosis
middle-aged or older persons
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CF of Seborrhoeic Keratosis
- Round, exophytic, coin-like plaques
- “Stuck-on” appearance
- Tan to dark brown colour
What do you observe? what skin disorder is this?
Disorder : Seborrhoeic Keratosis
obv: Dark brown, Round, exophytic, coin-like plaques
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Microscopic Findings:
* Monotonous sheets of small cells that resemble the basal cells of the normal epidermis
* Variable melanin pigmentation is present within these basaloid cells
* Hyperkeratosis at the surface
* Presence of small keratin-filled cysts (Horn cysts)
* Down-growth of keratin into the main tumour mass (Pseudo-Horn cysts)
features of?
Seborrhoeic Keratosis
Patho of Acitinic Keratosis
TP53 mutations caused by UV light-induced DNA damage
Risk factors of Acitinic Keratosis
Chronic exposure to sunlight
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Clinical presentation of Acitinic Keratosis
Small (<1cm), Rough, erythmatous(red) or brownish papules
- rough –> sandpaper- like on touch
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Macro features:
- red, scaly lesions w/ rough texture
Microscopic findings:
* Cytologic atypia in the lower portions of the epidermis
* Accompanying hyperplasia of basal cells or atrophy and diffuse thinning of the epidermal surface
* Thickened, blue-gray elastic fibers in the dermis (dermal solar elastosis)
* Thickened stratum corneum, with retained nuclei (parakeratosis)
features of?
Actinic Keratosis
* rough texture –> sand paper like
Acitinic Keratosis is asso. w/ an increased risk of developing?
SCC- Squamous Cell Carcinoma
Risk factors of SCC?
- Chronic exposure to sunlight (e.g. Acitinic Keratosis)
- Industrial carcinogens (tars and oils)
- Chronic ulcers
- Old burn scars
- Ingestion of arsenicals
- Ionising radiation
Epi of SCC
Older people; M > F
Patho of SCC
- TP53 mutations caused by UV light-induced DNA damage
- Mutations in HRAS
- Loss-of-function mutations in Notch receptors,
Clinical presentation of SCC in situ
Sharply defined, red, scaling plaques
Clinical presentation of invasive SCC
Nodular, with variable scale and ulceration
Micro features : Highly atypical cells at all levels of the epidermis, with nuclear crowding and disorganisation
Features of SCC in situ or Invasive SCC?
SCC in situ
Micro features: Penetration of the basement membrane
features of SCC in situ or invasive SCC?
Invasive (infiltrating) SCC
What do you observe? what skin condition causes this?
Disorder: SCC
Obv: sharply defined, ulcerative red lesions
CF of SCC
Ulcerative Red lesions (that appear on the face, lips and ears)
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What skin cancer presents w/ Keratin pearls on Histology?
Squamous Cell Carcinoma (Well-diffrentaited form)
Risk factors of Basal Cell Carcinoma
Chronic exposure to sunlight
Epi of Basal Cell Carcinoma
Older people
Patho of Basal Cell Carcinoma
Dysregulation of the Hedgehog pathway
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Clinical presentation of Basal Cell Carcinoma
- Pearly papules, often with prominent, dilated sub-epidermal blood vessels (Telangiectasia)
- Some tumours contain melanin pigment
What do you observe? What skin condition causes this?
Disorder: Basal Cell Carcinoma
Obv: A–> Paerly papule
B –> Dilated sub-epidermal blood vessels (Telangiectasia)
Microscopic Findings:
* Tumour cells resemble the normal epidermal basal cell layer
* Palisading (aligned) nuclei
* Separation of the peripheral border from the stroma (reduced stroma), with a creation of a characteristic cleft
features of?
Basal Cell Carcinoma
————: Benign congenital or acquired neoplasm of melanocytes
Melanocytic Naevus (Common mole)
Patho of Melanocytic Naevus
Activating mutation in BRAF
What strongly predisposes to Skin cancer?
Skin exposure
Epi of Melanocytic Naevus
Very common
Clinical presentation of Melanocytic Naevus
- Small papules; Size: ≤5 mm
- Tan-to-brown, uniformly pigmented
- Well-defined, rounded borders
the 3 types of Melanocytic Naevus
1) Compound
2) Junctional
3) intradermal naevus
What is the diffrence (Microscopically) btw Compound and Junctional Melanocytic Naevus ?
Junctional –> Nest of Mealnocytes grow along the dermo-epidermal junctions
Compound –> Melanocytes grow within the Dermis only
how do junctional / compound Melanocytic Naevus look like?
Compound–> well-defined, Brown nodule w/ rounded borders
Junctional –> Flat uniform bronw macule
micro: Epidermal nests lost entirely, and the cells grow into the underlying dermis in nests or cords
type of Melanocytic Naevus
Intradermal naevi
———– : Presence of a melanocytic lesion at birth
Congenital Naevus
what do you observe? Cause
medium and giant hairy naevus
syndrome: Congential Naevus
Microscopic Findings:
* Junctional component
* Stromal component
* Nevomelanocytes extend into the reticular dermis
* Patterns of dermal involvement: i. Diffuse, ii. Interstitial or iii. Perivascular
* Commonly, adnexal involvement
* Possible involvement of nerves
features of?
Congenital Naevus
Epi of Dysplastic Naevus
Sporadic or familial (Familial Dysplastic Naevus Syndrome)
patho of Dysplastic naevus
Activating mutation in BRAF
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CP of Dysplastic naevus
- Larger than acquired naevi (>5 mm)
- Numerous (in Familial Dysplastic Naevus Syndrome)
- Flat macules to slightly raised plaques, with a “pebbly” surface
- variable pigmentation (variegation) * Irregular borders
Macroscopic features:
- Uneven colour with dark brown centers and lighter, uneven edges
- Large and irregular in shape
Microscopic features:
- irregular nuclear contours & hyperchromasia
- Nevus cell nests within the epidermis may be enlarged and exhibit abnormal fusion or coalescence with adjacent nests (bridging)
- Melanin pigment that is phago- cytosed by dermal macrophages
- Subepidermal lamellar sclerosis (‘lamellar fibroplasia’)
features of?
Dysplastic Naevus
Risk factors of Melanoma
1) Sun exposure (intense)
2) Hereditary predisposition under Familial Dysplastic Naevus Syndrome
patho of melanoma
- Somatic activating mutations in the proto-oncogenes BRAF or NRAS
- Activating mutations in the c-KIT receptor tyrosine kinase
who is at most risk of Melanoma
Fair-skinned individuals
Clincial presentaitons of melanoma
- Rapid enlargement of a pre-existing naevus
- Itching or pain
- Development of a new pigmented lesion, during adult life
- Irregularity of the borders of a pigmented lesion
- Variegation of colour within a pigmented lesion
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THE ABCDE of melanoma
the 4 types of melanoma
1) Superficial spreading melanoma
2) Lentigo maligna
3) Nodular melanoma
4) Acral melanoma
state the diffrence (Macro) btw Superficial spreading melanoma and Letingo Maligna
Letingo maligna: Asymmetric complex macular pigmented lesion
Superficial spreading melanoma: Asymmetric comples Silhoutte
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Microscopic Findings:
* Malignant cells grow as poorly formed nests or as individual cells at all levels of the epidermis (pagetoid spread) and in expansile dermal nodules (radial and vertical growth phases)
* large nuclei with irregular contours
* Chromatin is characteristically clumped at the periphery of the nuclear membrane
* Prominent “cherry red” eosinophilic
nucleoli
features of?
Melanoma
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tumour marker used to detect melanoma
1) S-100
2) MART-2/ Melan-A
3) HMB45
4) AE1/AE3
5) Vimentin
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Prognosis of Melanoma
Depth of tumor (Breslow thickness) correlates w/ risk of metastasis
