Skin Pathologies
Eczema/Dermatitis
Inflammatory reaction of skin
Atopic eczema:
More common in children
Affects – knees, elbows, wrists and face
Flare ups due to irritants
Genetic link of defects in skin barrier repair and maintenance
Lack of AMP or mutation in filaggrin gene
Contact dermatitis:
Genetic link
Affects – hands, arms, face and legs
Allergic or irritant
Seborrheic dermatitis:
Affects – face, scalp, ears and skin folds
Yeast overgrowth
Symptoms – itchy, flaky and sore
Psoriasis
Genetic link
Keratinocytes normally take 3-4 weeks to migrate but takes 3-4 days in psoriasis
Skin cancers
Basal cell carcinoma – slow growing invasive tumours due to keratinocytes
Squamous cell carcinoma – invasive epidermal keratinocytes mainly effecting
men, elderly and due to topical carcinogens
Malignant melanoma – malignant melanocytes
Signs – asymmetry, border irregularities, colour variation, diameter >6mm and
changes over time
Pigmentation Disorders
Hypopigmentation – vitiligo, autoimmune and treated with phototherapy
Hyperpigmentation – caused by pregnancy and Addison’s disease
Wound Healing
Superficial – damage to epithelium heals rapidly
Partial thickness – involves dermal layer and vascular damage
Full thickness – involves subcutaneous fat and deeper taking a long time to heal
due to connective tissue regrowth
Haemostasis:
Microvascular injury causes bleeding
Vessels contract at efferent and 5-HT causes dilation of afferent
Coagulation cascade and platelet aggregation
Clot releases PDGF, EGF and TGF activating fibroblasts and macrophages
Early inflammatory stage:
Activation of complement
, Infiltration of neutrophils 24-48h and macrophages
Late inflammatory stage:
Blood macrophages arrive 48-72h for repair, cytokine and GF release plus
collagenase
Lymphocytes enter wound after 72h
Proliferative phase:
72h to 14 days
Fibroblast migration – proliferate producing ECM, collagen and proteoglycans
Collagen synthesis to strengthen
Angiogenesis – TGF and PDGF lead to formation
Granulation tissue formation – proliferating fibroblasts, ECM and vessels
Epithelialisation – single layer epithelial cells form next to wound edge
Remodelling phase:
Connective tissue mainly collagen and continued synthesis plus becomes
organised causing contraction
Fibroblasts and macrophages apoptose
Capillaries form and blood flow decreases
Chronic wound healing:
Local or systemic factors may alter the process or impair it
Presence of necrotic tissue, lack of blood supply, absence of granulation tissue,
pain, breakdown of ECM and infection
Skin Physiology and Inflammation
Eczema/Dermatitis
Inflammatory reaction of skin
Atopic eczema:
More common in children
Affects – knees, elbows, wrists and face
Flare ups due to irritants
Genetic link of defects in skin barrier repair and maintenance
Lack of AMP or mutation in filaggrin gene
Contact dermatitis:
Genetic link
Affects – hands, arms, face and legs
Allergic or irritant
Seborrheic dermatitis:
Affects – face, scalp, ears and skin folds
Yeast overgrowth
Symptoms – itchy, flaky and sore
Psoriasis
Genetic link
Keratinocytes normally take 3-4 weeks to migrate but takes 3-4 days in psoriasis
Skin cancers
Basal cell carcinoma – slow growing invasive tumours due to keratinocytes
Squamous cell carcinoma – invasive epidermal keratinocytes mainly effecting
men, elderly and due to topical carcinogens
Malignant melanoma – malignant melanocytes
Signs – asymmetry, border irregularities, colour variation, diameter >6mm and
changes over time
Pigmentation Disorders
Hypopigmentation – vitiligo, autoimmune and treated with phototherapy
Hyperpigmentation – caused by pregnancy and Addison’s disease
Wound Healing
Superficial – damage to epithelium heals rapidly
Partial thickness – involves dermal layer and vascular damage
Full thickness – involves subcutaneous fat and deeper taking a long time to heal
due to connective tissue regrowth
Haemostasis:
Microvascular injury causes bleeding
Vessels contract at efferent and 5-HT causes dilation of afferent
Coagulation cascade and platelet aggregation
Clot releases PDGF, EGF and TGF activating fibroblasts and macrophages
Early inflammatory stage:
Activation of complement
, Infiltration of neutrophils 24-48h and macrophages
Late inflammatory stage:
Blood macrophages arrive 48-72h for repair, cytokine and GF release plus
collagenase
Lymphocytes enter wound after 72h
Proliferative phase:
72h to 14 days
Fibroblast migration – proliferate producing ECM, collagen and proteoglycans
Collagen synthesis to strengthen
Angiogenesis – TGF and PDGF lead to formation
Granulation tissue formation – proliferating fibroblasts, ECM and vessels
Epithelialisation – single layer epithelial cells form next to wound edge
Remodelling phase:
Connective tissue mainly collagen and continued synthesis plus becomes
organised causing contraction
Fibroblasts and macrophages apoptose
Capillaries form and blood flow decreases
Chronic wound healing:
Local or systemic factors may alter the process or impair it
Presence of necrotic tissue, lack of blood supply, absence of granulation tissue,
pain, breakdown of ECM and infection
Skin Physiology and Inflammation
