Histopathology - Skin Pathology Flashcards
What are the different layers of the epidermis from superficial to deep?
Come Let’s Get Sun Burnt
- (Stratum) Corneum
- (Stratum) Lucidum
- (Stratum) Granulosum
- (Stratum) Spinosum
- (Stratum) Basale
- Basement membrame of epidermis
What is the dermis and what components is it made up of?
A vascularised supporting structure
- Collagen fibres
- Elastin fibres
- Adnexal structures
- Eccrine glands
- Sebaceous glands
- Hair follicles
What are some features of the epidermis?
- Thin, avascular outer layer (15-30 day turnover)
- Functions as barrier
- Squamous epithelial cells
- Comprised of keratinocytes
What cell types are seen in the epidermis?
- Stratum disjunctum
- Corneocyte
- Granular keratinocyte
- Langerhans cells
- Spinous keratinocyte
- Epidermal basal cell
- Melanocyte
What is hyperkeratosis?
Increase/thickening of S. Corneum
- Increase in keratin
What is parakeratosis?
Nuclei in S. corneum
- Thickening of skin when scratching it
What is acanthosis?
Increase in S. spinosum
What is acantholysis?
Decrease in cohesions between keratinocytes
What is spongiosis?
Intercellular oedema (between keratinocytes)
What is lentiginous?
- Linear pattern of melanocyte proliferation within epidermal basal cell layer (reactive or neoplastic)
What is lichenoid?
Sheeny plaque appearance on surface of skin
What is psoriaform?
Thickened skin
What are the two aetiological theories of dermatitis/eczema?
Inside-out:
- Immune system (autoimmune) causes IgE sensitisation resulting in skin barrier dysfunction
Outside-in:
- Defective skin barrier with an allergen exposure reesults in IgE sensitisation
What are the six inflammatory reaction patterns?
- Lichenoid
- Psoriaform
- Spongiosis
- Vesicobullous
- Vasculitis
- Granulomatous
What is vesicobullous?
Forms bullae
What is vasculitis?
Associated with vasculitis
What is granulomatous?
Associated with granulomas
What is the acute histology of dermatitis?
- Fluid collection in dermis (spongiosis)
- Eosinophil infiltrate in dermis
- Dilated dermal capillaries
- Thickening of epidermis
What is the chronic histology of dermatitis?
- Acanthosis
- Crusting
- Scaling
- T cells
- Eosinophils
- Hyperparakeratosis
What are the three types of dermatitis?
- Atopic
- Contact
- Seborrhoeic
What are the clinical features of Atopic Dermatitis?
Infants:
- Face
- Scalp
- Extensor surfaces
- Persists into adulthood in those with FHx of atopy
Adults:
- Flexural areas
Chronic:
- Lichenification
IgE-Mediated (Type 1)
What are the clinical features of Contact dermatitis?
- Type IV hypersensitivity (e.g. to nickel, rubber)
- Erythema
- Swelling
- Pruritis
- Commonly affects ear lobes + neck (from jewellery), wrist (leather watch straps), feet (shoes)
What are the clinical features of Seborrhoeic dermatitis?
- Inflammatory reaction to a yeast (Malassezia furfur)
Infants:
- Cradle cap
- Large, yellow scales on scalp
- Nappy sites
Young adults:
- Mild erythema
- Fine scaling
- Mildly pruritic
- Affects face, eyebrow, eyelid, anterior chest, external ear
What is psoriasis?
- Chronic inflammatory dermatosis with erythematous, well demarcated scaly plaques (salmon-pink)
- Early (15-25yrs) + Late (50-60yrs) bi-modal distribution
What is the pathophysiology of psoriasis?
- Type IV T cell hypersensitivity reaction within epidermis
- Further T cell recruitment
- Release of pro-inflammatory cytokines (TNF-α, IFN-gamma)
- Keratinocyte hyperproliferation
- Epidermal thickening
What is seen on histology of psoriasis?
- PARAKERATOSIS
- Neutrophilia
- Loss of granular layer (Stratum Granulosum)
- Clubbing of Rete Ridges - Test tubes in rack appearance
- Munro’s microabscesses (neutrophil recruitment)
- Dilated blood vessels
What are the five types of psoriasis and which is most common?
- Chronic plaque psoriasis (Most common)
- Flexural psoriasis
- Guttate psoriasis
- Erythrodermic/pustular psoriasis (Emergency)
- Koebner phenomenon
What are the features of chronic plaque psoriasis?
- Salmon pink plaques
- Silver scales
- Affects Extensor aspects of knees, elbows + scalp
What are the features of flexural psoriasis?
- Seen in later life
- Usually groin, natal cleft + sub-mammary areas
What are the features of Guttate psoriasis?
- Rain-drop plaque distribution
- Often in children
- On trunk
- Usually 2wks post Group A Β-haemolytic Strep infection
What are the features of Erythrodermic/pustular psoriasis?
- Emergency
- Severe widespread disease
- Systemic Sx
- Can be limited to hands + feet (palmo-plantar psoriasis)
What are the features of Keobner phenomenon?
- Plaques form at/along trauma sites
What is Auspitz’ sign?
Rubbing psoriatic plaques causes pin-point bleeding
What is psoriasis associated with?
(POSHDASS)
Nail changes:
- P: Pitting
- O: Onycholysis
- S: Subungual H: Hyperkeratosis
Arthritis (5-10%)
- D: DIP Disease
- A: Arthritis multilans “Telescoping”
- S: Spondylopathy
- S: Symmetrical polyarthritis
What is the appearnce of Lichen Planus lesions?
5Ps:
- Pruritic
- Purple
- Polygonal
- Papules
- Plaques
With:
- Mother-of-pearl sheen
- Fine white network on surface (Wickam’s striae)
Where is lichen planus typically seen?
- Inner surfaces of wrists
- ?Oral mucous membrane (lesions have lacy appearance)
What is the pathophysiology of lichen planus?
- Accumulation of T cells attacking basement membrane
What is seen on histology for lichen planus?
- Hyperkeratosis
- SAW-TOOTHING OF RETE RIDGES
- Basal cell degeneration
What is the typical appearance of erythema multiforme and where is it most commonly seen?
- Annual target lesion
- Pleomorphic lesions
- Combination of macules, papules, urticarial weals, vesicles, bullae + petechiae
- Commonly on extensor surfaces of hands + feet
What are the causes of erythema multiforme?
Infections:
- HSV
- Mycoplasma
Drugs (SNAPP):
- S: Sulphonamides
- N: NSAIDs
- A: Allopurinol
- P: Penicillin
- P: Phenytoin
What is the spectrum of disease severity in regards to erythema multiforme?
- Erythema multiforme
- Steven Johnson’s syndrome (SJS)
- Toxic epidermal necrolysis
What is Steven Johnson’s syndrome/toxic epidermal necrolysis?
- Dermatological emergency
- Sheets of skin detachment (<10& in SJS + >30% in TEN)
- Prominent mucosal involvement
- Nikolsky sign +ve
What is tehe common cause of Steven Johnson’s syndrome/toxic epidermal necrolysis?
Drugs
- Sulfonamide Abx
- Anticonvulsants
What are the different types of bullous disease?
- Dermatitis herpetiformis
- Bullous pemphigoid
- Pemphigus vulgaris
- Pemphigus foliaceus
What is the pathophysiology of dermatitis herpetiformis?
- A/W: Coeliac
- IgA Abs bind to basement membrane, leads to subepidermal bulla
What are the clinical features of dermatitis herpetiformis?
- Itchy vesicles on extensor surfaces of elbows + buttocks
What are the histological features of dermatitis herpetiformis?
- Microabscesses which coalesce to form subepidermal bullae
- Neutrophil + IgA deposits at tips of dermal papillae
What is the pathophysiology of Bullous Pemphigoid?
- IgG Abs + C3 bind to hemidesmosomes (adhesion molecule of basement membrane)
- Epidermis lifts off
- Fluid accumulates in space
- SUBepidermal bulla
What are the clinical features of Bullous Pemphigoid?
- Large, tense bullae on erythematous base
- Often on flexural surfaces (forearms, groin + axillae)
- ELDERLY
- Bullae do not easily rupture as easily as pemphigus
What are the histological features of Bullous Pemphigoid?
- Subepidermal bullae
- EOSINOPHILIA
- Linear deposition of IgG along basement membrane
What is the pathophysiology of Pemphigus Vulgaris?
- IgG Abs bind to desmoglein 1 + 3 (adhesion molecules) between keratinocytes in S. Spinosum
- Acantholysis
- INTRAepithelial bulla
What are the clinical features of Pemphigus Vulgaris?
- Bullae are easily ruptured
- Raw, red surface
- Flaccid blisters
- Found on skin + mucosal membranes
- Nikolsky’s sign +ve
- Mucosal involvement
What are the histological features of Pemphigus Vulgaris?
- Intraepithelial bulla
- Netlike pattern of intercellular IgG deposits
- Acantholysis
What is the pathophysiology of Pemphigus Foliaceus?
- IgG against desmoglein 1 in epidermis
- Detachment of superficial keratinocytes
- Attacks outer layer of keratinocytes in S. Corneum
What are the clinical features of Pemphigus Foliaceus?
- Very rare
- No intact bullae
- Appears excoriated
- Affects elderly population
What are the histological features of Pemphigus Foliaceus?
- 3 levels of split
What is a type of benign cutaneous neoplasm?
Seborrhoeic keratosis
What are the characteristics and histological features of seborrhoeic keratosis?
Character:
- Rough plaques
- Waxy
- “Stuck on”
- Appear in middle age/elderly
Histo:
- Keratin horns in epidermis
- Orderly proliferation
What are the premalignant cutaneous neoplams?
- Actinic (Solar/Senile) Keratosis
- Keratoacanthoma
- Bowen’s disease (SCC in situ)
What are the characteristics and histological features of Actinic Keratosis?
Character:
- Rough
- Sandpaper like texture
- Scaly lesions
- On sun-exposed areas
Histo (SPAIN):
- S: Solar elastosis
- P: Parakeratosis
- A: Atypical cells
- I: Inflammation
- N: Not full thickness
What are the characteristics and histological features of keratoacanthoma?
Character:
- Rapidly growing
- Dome-shaped nodule
- ?Necrotic, crusted centre
- Grows over 2-3wks
- Clears spontaneously
Histo:
- Similar to SCC, hard to differentiate
What are the characteristics and histological features of Bowen’s disease?
Character:
- Intra-epithelial squamous cell carcinoma in situ
- Flat
- Red
- Scaly
- Patches
- Sun-exposed areas
Histo:
- Full thickness
- Atypia/dysplasia
- Basement membrane intact (not invading dermis)
What are the two types of malignant skin cancer and which is most common?
- Squamous Cell Carcinoma (2nd most common)
- Basal Cell Carcinoma (Most common)
What are the characteristics and histological features of Squamous Cell Carcinoma?
Character:
- When Bowen’s has spread to involve dermis
- Ulcerative
- Crusting
- Hyperkeratotic
- +/- Rolled edges
- Moderately growing
- Can metastasise
- Locally destructive
Histo:
- Atypia/dysplasia throughout epidermis
- Nuclear crowding + spreading through basement membrane into dermis
What are the characteristics and histological features of Basal Cell Carcinoma?
Character:
- Rodent ulcer
- Slow growing tumour
- Rarely metastastic
- Locally destructive
- Sun-exposed areas
- Well-defined
- Rolled edges
- Pearly surface
- Often telangietasia
Histo:
- Mass of basal cells pushing down into dermis
- Palisading (nuclei align in outermost layer)
What is a benign melanocytic condition and its features?
Melanocytic naevi (moles)
- Junctional
- Compound
- Intradermal
What are the histological features of Malignant Melanomas?
- Atypical melanocytes
- Initially grow horizontally in epidermis (radial growth phase)
- Then grow vertically into dermis (vertical growth phase)
- Vertical growth produces BUCKSHOT APPEARANCE (Pagetoid cells)
What is Breslow thickness?
Most important prognostic factor based off depth (every mm worsens prognosis)
What is the spread of malignant melanomas?
More commonly to lymph nodes than blood
What are some worrying symptoms associated with malignant melanomas?
- Bleeding
- Itching
- Growing
What are the four types of malignant melanomas, their prevalence and basic features ?
Superficial spreading
- Most common
- Irregular borders
- Variation in colour
Nodular
- 2nd most common
- Can occur on all sites
- More common in younger age group
Lentigo maligna
- Occurs on sun exposed areas of elderly caucasians
- Flat
- Slow growing black lesion
Acral lentiginous
- Rare
- Occurs on palms, soles + subungual areas
What are the features of pityriasis rosea?
- Salmon pink rash appears first (HERALD PATCH), followed bu oval macules in christmas tree distribution
- Appears after HHV6 + HHV7 infections
- Remits spontaneously
