Chronic exposure to sunlight (e.g. Acitinic Keratosis) Industrial carcinogens (tars and oils) Chronic ulcers Old burn scars Ingestion of arsenicals Ionising radiation

TP53 mutations caused by UV light-induced DNA damage Mutations in HRAS Loss-of-function mutations in Notch receptors,

Skin I (b) Flashcards by Elyaa Saleh

patho of Seborrhoeic Keratosis

Mutations in fibroblast growth factor (FGF) receptor 3

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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

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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

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Patho of Acitinic Keratosis

TP53 mutations caused by UV light-induced DNA damage

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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

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Acitinic Keratosis is asso. w/ an increased risk of developing?

SCC- Squamous Cell Carcinoma

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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

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Epi of SCC

Older people; M > F

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Patho of SCC

TP53 mutations caused by UV light-induced DNA damage
Mutations in HRAS
Loss-of-function mutations in Notch receptors,

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Clinical presentation of SCC in situ

Sharply defined, red, scaling plaques

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Clinical presentation of invasive SCC

Nodular, with variable scale and ulceration

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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

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Micro features: Penetration of the basement membrane

features of SCC in situ or invasive SCC?

Invasive (infiltrating) SCC

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What do you observe? what skin condition causes this?

Disorder: SCC
Obv: sharply defined, ulcerative red lesions

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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)

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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

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

# ** 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

# ** 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**

# ** 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**

# ** tumour marker used to detect melanoma

1) **S-100** 2) MART-2/ Melan-A 3) **HMB45** 4) AE1/AE3 5) Vimentin

# ** Prognosis of Melanoma

Depth of tumor **(Breslow thickness)** correlates w/ risk of metastasis