Rashes Flashcards
What is hyperkeratosis?
Increased thickness of the keratin layer
What is parakeratosis?
Persistence of nuclei in the keratin layer
What is acanthosis?
Increased thickness of the epithelium
What is papillomatosis?
Irregular epithelial thickening
What is spongiosis?
Intercellular oedema develops in the epidermis
What are the 4 main reaction patterns of inflammatory skin diseases?
Spongiotic
Psoriasiform
Lichenoid (basal layer damage)
Vesiculobullous (blistering)
What are examples of each reaction pattern of inflammatory skin disease?
Spongiotic - interaepidermal oedema
Psoriasiform - psoriasis
Lichenoid - lichen plan’s, SLE
Vesiculobullous - pemphigoid, pemphigus, dermatitis herpetiformis
What is psoriasis?
A common chronic inflammatory dermatosis
What is the pathology of psoriasis?
Unclear
Complement attracts neutrophils to the keratin layer
What is the clinical presentation of psoriasis?
Symmetrical bilateral well-demarcated silvery or erythematous plaque
Nail changes - onycholysis, pitting, hyperkeratosis
Extensors, scalp, etc
What is acute psoriasis?
Covering body
Underlying cutaneous lymphoma, drug reaction or psoriasis
Manage as if severe widespread burn
What is the histological appearance of psoriasis?
Elongation of ridges, which become club-shaped and fuse with neighbouring ridges
Few lymphocytes in dermis
Neutrophil polymorphs
Abscesses
What are lichenoid disorders?
Conditions characterised by damage to basal epidermis
What is the most common lichenoid disorder?
Lichen planus
What is the clinical presentation of lichenoid disorders?
Itchy flat-topped raised papules
What is the histological appearance of lichenoid disorders?
Irregular sawtooth acanthuses (thickening of epidermis)
Hypergranulosis (thickened granular layer) and hyperkeratosis (thickened keratin later)
Infiltrate of lymphocytes
Basal damage with formation of cytoid bodies
What is pemphigus?
A group of rare autoimmune bullous diseases
Loss of integrity of epidermal cell adhesion
All involve acantholysis
Intraepidermal
What is acantholysis?
Lysis of intercellular adhesion sites
What patients usually present with pemphigus?
Middle aged
What is the treatment for pemphigus?
Steroids
What is the most common variant of pemphigus?
Pemphigoid vulgaris
What is the pathophysiology of pemphigoid vulgaris?
IgG auto-antibodies attack desmoglein 3, the protein that maintains desmosome attachments
Immune complexes form on cell surface and activates complement, causing protease release
Disruption of desmosomes causes acantholysis
What is the clinical presentation of pemphigoid vulgaris?
Fluid filled blisters which rupture to form shallow erosions
Involves skin, especially scalp, face, axillae, groin, trunk
May affect mucosa
How is diagnosis of pemphigoid vulgaris done?
Immunofluorescence - chickenwire pattern
What is bullous pemphigoid?
Sub-epidermal blister
No acantholysis
What is the pathophysiology of bullous pemphigoid?
IgG antibodies attack the hemidesmosomes anchoring basal cells to the basement membrane
This causes local complement activation and tissue damage
How is diagnosis done for bullous pemphigoid?
Immunofluorescence - linear pattern
Histology for early lesions
What is dermatitis herpetiformis?
Rare autoimmune bullous disease
Associated with coeliac, 90% have gluten sensitive enteropathy
What is the clinical presentation of dermatitis herpetiformis?
Intensely itchy symmetrical lesions
Elbow, knees and buttocks
Papollary dermal microabscesses
What is the pathophysiology of dermatitis herpetiformis?
IgA antibodies target gliadin component of gluten and cross react with connective tissue matrix proteins
Immune complexes form in dermal papillae and activate complement and generateneutrophil chemotaxins
How is dermatitis herpetiformis diagnosed?
Immunofluorescence - granular IgA deposits in dermal papillae
Where are the common sites for acne?
Sebaceous gland sites - face, upper back, anterior chest
What is the aetiology of acne?
Androgens are released in puberty
Sebaceous glands are sensitised to androgen
Keratin plugging of pilosebaceous units
Infection with anaerobic bacterium corynebacterium acnes
What does keratin and sebum build up produce?
Comedones (black and whiteheads)
How does rosacea present?
Recurrent facial flushing
Visible blood vessels
Pustules
Thickening of the skin
Who tends to get rosacea?
10% in caucasian adults
Commoner in females
Aged 30-60
What are some factors that can trigger rosacea?
Sunlight Alcohol Spicy foods Stress Tetracyclines
What is the pathology of rosacea?
Vascular ectasia
Patchy inflammation with plasma cells
Pustules
Perifollicular granulomas
What are risk factors for psoriasis?
15-25 y/os, 50-60 y/os
Environmental factors - stress, drugs (beta blockers), previous infection
Family history
What are common comorbidities in psoriasis?
Psoriatic arthritis Metabolic syndrome Crohn's disease Cancer Depression Uveitis
What is the management for psoriasis?
Emollients Vitamin D analogues Coal tar Dithranol Steroid ointments Phototherapy Immunosuppression
What is the management for acne?
Benzoyl peroxide
Vitamin A derivatives
Antibiotics
Isotretinoin
What are the morphological features of acne?
Comedones (black and white heads)
Pustules and papules
Cysts
Erythema
What is the management for rosacea?
Reduce aggravating factors (dietary triggers, sun exposure, topical steroids)
Metronidazole
Oral tetracycline
What is the management for lichenoid disorders?
Emollients
Symptomatic treatment (steroids)
Phototherapy
What is the difference between bullous pemphigoid and pemphigus?
BP - split is deeper, through the derma-epidermal junction
P - split is more superficial, intra-epidermal
What are the investigations for bullous pemphigoid and pemphigus?
Skin biopsy and immunofluorescence
What is the management for bullous pemphigoid and pemphigus?
Systemic steroids
Immunosuppression
Emollients
Tetracycline antibiotics in pemphigoid
