skin Flashcards by Elyaa Saleh

Patho of Urticaria

Immediate (type 1) hypersensitivity reaction -> corss-linkage of IgE on mast cells which cause degranualtion

How well did you know this?

Not at all

Perfectly

Microscopic Findings:
* Superficial perivenular infiltrate of mononuclear cells (Lymphatic vessel dilatation)
* Superficial dermal oedema, creating more widely spaced collagen bundles
* Degranulation of mast cells,

features of?

Urticaria

How well did you know this?

Not at all

Perfectly

Degranulation of mast cells in Urticaria can highlighted using ——– stain

Giemsa stain

How well did you know this?

Not at all

Perfectly

CP of Urticaria

Erythematous, oedematous, and Pruritic wheals(form after the degranulation of mast cells)

How well did you know this?

Not at all

Perfectly

cause of Allergic Contact Dermatitis

Type IV hypersensitivity reaction secondary to contact allergens (e.g, poison ivy, nickel)

How well did you know this?

Not at all

Perfectly

CP of allergic contact dermatitis

localized pruritic (itchy) skin lesions, blisters w/ clear fluid

* bullae: blisters w/ clear fluid

How well did you know this?

Not at all

Perfectly

Microscopic Findings:
* Spongiosis (epidermal odema)
* Intercellular bridges are stretched
* Superficial perivascular lymphocytic infiltrate
* Oedema of dermal papillae
* Mast cell degranulation

features of?

Allergic Contact Dermatitis

*note very similar micro features of Urticaria

How well did you know this?

Not at all

Perfectly

CP of Erythema Multiforme

Target- like papules
(consisting of red macules or papules with pale vesicular or eroded centers)

How well did you know this?

Not at all

Perfectly

Macroscopic features:
* pathces have pale, vesicular, or eroded centers (Target-like papules)

Microscopic Findings:
* Dermal oedema
* lesions w/ degenerating (apoptotic) keratinocytes w/ lymphocytic infiltrates

Erythema Multiforme

*keratinocytes: the major cell type of the epidermis

How well did you know this?

Not at all

Perfectly

CP of Psoriasis

pink to salmon-coloured palques w/ silvery scaling

How well did you know this?

Not at all

Perfectly

Microscopic Findings:
* Epidermal thickening (acanthosis), w/ parakeratotic (nuclei still in stratum corneum)
* loss of the stratum granulosum and parakeratotic scale (due to lack of maturation)
* Regular elongation of the rete ridges
* Thinning of the epidermal cell layer overlying the tips of dermal papillae

Features of?

Psoriasis

How well did you know this?

Not at all

Perfectly

patho of Linchen PLanus

* chronic inflammatory skin disorder

CD8+ T cell-mediated cytotoxic immune response against antigens in the basal cell layer and the dermo-epidermal junction

How well did you know this?

Not at all

Perfectly

CP of Lichen Planus

6 P’s
1) Pruritic, purple, polygonal, planar papules, and plaques of skin and squamous mucosa
2) Mucosal involvement –> Wickham striae

How well did you know this?

Not at all

Perfectly

Microscopic Findings:
* The lymphocytes are intimately associated with basal keratinocytes, which often atrophy or become necrotic
* “zig-zag” contour/”saw-tooth” infiltrate of lymphocytes at Dermo-epidermal interface (junction)
* Presence of anucleate, necrotic basal cells (colloid bodies or Civatte bodies)

features of?

Lichen Planus

How well did you know this?

Not at all

Perfectly

cause of Lichen simplex Chronicus

Response to local repetitive trauma, such as continual rubbing or scratching

How well did you know this?

Not at all

Perfectly

CP of Lichen Simplex Chronicus

Raised, erythematous, and scaly lesions

How well did you know this?

Not at all

Perfectly

Microscopic Findings:
* Acanthosis (epi thickening)
* Hyperkeratosis
* Hypergranulosis ( ↑ thickness of the stratum granulosum)
* Solar elastosis
* Elongation of the rete ridges
* Fibrosis of the papillary dermis
* Dermal chronic inflammatory infiltrate

features of?

Linchen Simplex Chronicus

How well did you know this?

Not at all

Perfectly

cause of Impetigo

* superficial bacterial infection

Staphylococcus aureus, Streptococcus pyogenes

How well did you know this?

Not at all

Perfectly

CP of Impetigo

lesions w/ Honey-coloured crusting

How well did you know this?

Not at all

Perfectly

Microscopic Findings:
* Accumulation of neutrophils beneath the stratum corneum that often produces a sub-corneal pustule
* Superficial dermal inflammation accompany these findings
* Bacterial cocci in the superficial epidermis (demonstrated by Gram stain)

features of?

impetigo

How well did you know this?

Not at all

Perfectly

obv+ skin condition

Skin condition: Superficial dermal fungal infection caused by Candida albicans
Obv: Satelite lesions

How well did you know this?

Not at all

Perfectly

Microscopic Findings:
*Neutrophilic infiltrate in the epidermis
*Psoriasiform hyperplasia

Candidiasis of the Skin

Psoriasiform hyperplasia-> Candida

How well did you know this?

Not at all

Perfectly

Stain used for Candida causing superfical Dermal fungal infection

PAS

How well did you know this?

Not at all

Perfectly

Obv+ skin disorder

Condition: Deep dermal fungal infection caused by Apergillus
Obv: A- Erythematous subcutaneous nodule
B- Focally haemorrhagic lesion

How well did you know this?

Not at all

Perfectly

Histochemistry for Deep Dermal fungal infection caused by Aspergillus

1) PAS- Periodic Acid-Schiff 2) Gomori methenamine silver stains | *identify fungal organisms

cause of Verrucae (Warts) | * viral infection

Human Papilloma Virus (HPV)

Microscopic Findings: * Epidermal hyperplasia * Cytoplasmic vacuolisation [koilocytosis] (preferentially of the more superficial epidermal layers) --> **Halos of pallor surrounding infected nuclei** * Infected cells with **prominent kerato-hyalin granules** and **jagged eosinophilic intracytoplasmic protein aggregates** (result of impaired maturation) features of?

Verrucae (Warts)

the 4 types of Verrucae (Wrats)

1. **Verruca Vulgaris** 2. Verruca Plana (Flat Wart) 3. Verruca Plantaris/Palmaris 4. Condyloma Acuminatum (Venereal Wart)

most common type of Verrucae (Wrats)

**Verruca Vulgaris**

loc of Verruca Vulgaris

dorsum of the hand

Verucca Vulgaris presents w/ Rough, --------------to --------------- skin coloured papule/plaque Macroscopically

hyperkeratotic to papillomatous | Hyperkeratotic --> thickening of the outer layer of the skin

Macroscopic features: - Rough, **hyperkeratotic to papillomatous skin coloured papule/plaque** microscopic features : - Papillomatous hyperplasia - Prominent granular layer - **Inward bending of rete** - Koilocytosis features of ?

Veruuca Vulgaris

# ** what type of Verruca (Wrats) has the following microscopic features: - Multiple **“bird’s eye” nuclei** in the granular cell layer

**Verruca Plana**

Macroscopic features: - Warty **cauliflower-like lesion** w/ papillary or polypoid fronds Microscopic features : - Papillomatous mammillated epithelial hyperplasia - Koilocytic changes - Hyperkeratosis features of?

Condyloma Acuminatum (Venereal Wart)

patho of Pemphigus

* **Antibody-mediated (type II) hypersensitivity reactions** * **IgG auto-antibodies** that bind to intercellular desmosomal proteins (Desmoglein types 1 and 3) of skin and mucous membranes

Microscopic Findings: * **Acantholysis**: Lysis of the intercellular adhesive junctions between neighbouring squamous epithelial cells that results in the rounding up of detached cells * **Superficial dermal infiltrates comprised of lymphocytes, macrophages, and eosinophils** features of?

Pemphigus

Direct Immuno-Fluorescence of Pemphigus

Fishnet-like pattern of intercellular IgG deposits

* Acantholysis selectively involves the layer of cells immediately above the basal cell layer, giving rise to a supra-basal acantholytic blister what type of Pemphigus is this?

Pemphigus Vulgaris

# ** microscopic features; - **Acantholysis in the granular cell layer with “missing” stratum corneum** - Neutrophils in the granular cell layer - Separation of the corneum from the rest of the epidermis features of?

Pemphigus Foliaceus

Microscopic Findings: * Perivascular infiltrate of lymphocytes and variable numbers of eosinophils, occasional neutrophils * Superficial dermal oedema * Associated basal cell layer vacuolisation; The vacuolated basal cell layer eventually gives rise to a **fluid-filled sub-epidermal non-acantholytic blister** features of?

Bullous Pemphigoid

Direct Immuno-Fluorescence of Bullous Pemphigoid

Linear deposition of IgG antibodies and complement in the epidermal basement membrane

Epi of Dermatitis Herpetiformis

* Males * 80% occurs is **ass. w/ Coeliac disease**

patho of Dermatiis Herpetiformis

Genetically predisposed persons develop: *** IgA antibodies to dietary Gluten** (derived from the wheat protein Gliadin) and ***IgA auto-antibodies that cross-react with epidermal transglutaminase** , expressed by keratinocytes

# ** CP of Dermatitis Herpetiformis

Pruritic urticaria and **grouped vesicles**

# ** Microscopic Findings: * **Neutrophils accumulate selectively at the tips of dermal papillae**, forming small micro-abscesses- **"Papillary Abscess"** * The basal cells overlying these micro-abscesses show vacuolisation and focal **dermo-epidermal separation** that ultimately coalesce to form subepidermal blisters features of?

Dermatitis Herpetiformis

# ** CF of Seborrhoeic Keratosis

* Round, exophytic, **coin-like plaques** * **“Stuck-on” appearance** * **Tan to dark brown colour**

# ** 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

# ** Clinical presentation of Acitinic Keratosis

Small (<1cm), **Rough**, erythmatous(red) or brownish papules * rough --> **sandpaper- like on touch**

# ** 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

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

# ** What skin cancer presents w/ **Keratin pearls** on Histology?

Squamous Cell Carcinoma (Well-diffrentaited form)

Epi of Basal Cell Carcinoma

Older people

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

Patho of Melanocytic Naevus

Activating mutation in BRAF

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

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

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

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

# ** 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