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Dermatology and Infectious Diseases Disorders of Keratinisation Dermatitis Blistering Disorders Immunology Disorders of Keratinisation Overview Psoriasis Icthyosis Objectives Disorders of Keratinisation Disorders of Keratinization Keratinization Terminal differentiation of epithelia – epithelial proteins (Keratin) – Glycoproteins (Cell Envelope) – intercellular lipids Disorders of Keratinization Cause changes in the skin – Dry, Scaly, Thickened, Flaky – Blistering Cause changes in Mucous membranes, Nails and Hair Disorders of Keratinization Change in Type of Keratin Made Disorders of Keratinisation Disorders of Keratinisation Disorders of Keratinization Psoriasis Icthyosis Disorders of Keratinization Psoriasis Chronic , relapsing and remitting skin disease. May appear at any age may affect any part of the skin Common Locations: – Extensor surfaces Knees and Elbows Disorders of Keratinization Psoriasis Characterised by hyperproliferation of skin and inflammation Disorders of Keratinization Psoriasis Etiology – Inherited • Abnormality of Ca++ metabolism • Genetic Predisposition – HLA Cw6 – HLA DR7 – HLA B27 (Pustular) Disorders of Keratinization Psoriasis Etiology – Environmental Factors • Stress, Smoking and Alcohol • Systemic Drugs • Infection – Immunological Factors Psoriasis Gawkrodger, D.J. (1992) Dermatology. Edinburgh: Churchill Livingston. (1992) Disorders of Keratinization Psoriasis Abnormalities in Psoriatic Skin – transit time through epidermis – mitotic activity – rate of DNA synthesis – high levels of Ca++ binding protein calmodulin – Presence of keratin 6 & 16 in epidermis • These five are must knows Disorders of Keratinization Psoriasis Abnormalities in Psoriatic Skin – levels of phospholipase A2 activity – levels of polyamine synthesis – levels of plasminogen activator – cGMP levels leading to a high ratio cGMP/cAMP • These 4 are included for the sake of completeness Disorders of Keratinization Psoriasis Pathology – Stratum Corneum • contains nuclei – Stratum granulosum • doesn’t exist – Stratum Spinosum • expanded • bulbous downward projections • mitosis Disorders of Keratinization Psoriasis Pathology contd. – Papillary Dermis • Papillae thickened • large dilated thin walled blood vessels – Dermis/Epidermis • infiltrated with leukocytes • in Stratum corneum these clump together to form Spongiform pustules (aka Munro microabscesses) Psoriasis Gawkrodger, D.J. (1992) Dermatology. Edinburgh: Churchill Livingston. (1992) Psoriasis Koebner Phenomenon Gawkrodger, D.J. (1992) Dermatology. Edinburgh: Churchill Livingston. (1992) Required Reading Gawkrodger, D.J. (1992) Dermatology. Edinburgh: Churchill Livingston. (1992) Psoriasis Disorders of Keratinisation Icthyoses A variety of hereditary keratinisation disorders visible scales on the skin Forms include – autosomal dominant – x-linked – associated with multisystem changes Disorders of Keratinisation Icthyoses May vary from very mild to very severe The keratinisation process which is changed varies from condition to condition Icthyosis Gawkrodger, D.J. (1992) Dermatology. Edinburgh: Churchill Livingston. (1992) Required Reading Gawkrodger, D.J. (1992) Dermatology. Edinburgh: Churchill Livingston. on Keratinization and Blistering Syndromes Dermatitis/eczema dermatitis = eczema non-infective inflammation of the skin Greek for ‘to boil over’ reaction to various stimuli – some known, some unknown Dermatitis Classification current classification unsatisfactory/inconsistent distinctions are often difficult to determine endogenous (internal factors) exogenous (external factors) acute chronic Dermatitis Acute acute eczema leads to epidermal oedema (spongiosis), with separation of keratinocytes leads to epidermal vesicles dermal vessels become dilated inflammatory cells invade the dermis and epidermis Dermatitis Chronic chronic eczema leads to a thickening of the stratum spinosum (acanthosis) & stratum corneum (hyperkeratosis) also get retention of nuclei by some corneocytes rete ridges are lengthened dermal vessels are dilated inflammatory mononuclear cells infiltrate the skin Dermatitis Gawkrodger, D.J. (1992) Dermatology. Edinburgh: Churchill Livingston. (1992) Dermatitis Types of dermatitis/eczema contact dermatitis/eczema – contact with an irritant atopic dermatitis/eczema – associated with a history of asthma, allergic rhinitis, conjunctivitis seborrhoeic dermatitis/eczema – commonly affects the scalp and face Dermatitis Types of dermatitis/eczema cont. discoid (nummular) dermatitis/eczema – often presents as coin-shaped lesions on the limbs of middle aged or older people venous stasis dermatitis/eczema – associated with venous disease – commonly involves the medial aspect of the ankle Required Reading Gawkrodger, D.J. (1992) Dermatology. Edinburgh: Churchill Livingston., D.J. (1992) Dermatology. Edinburgh: Churchill Livingston. Chapters on Eczema Bullous Disorders blistering (bullous) disorders are often seen with skin disease found with common skin conditions like acute contact dermatitis Etiology-autoimmune mechanisms, inheredited errors in metabolism and mechanical trauma Types of Bullous Disorders Pemphigus Systemic lupus Pemphigoid erythematosis (SLE) Erythema multiforme Stevens-Johnson syndrome Bullous impetigo Bullous diabeticorum Epidermolysis bullosa dermatitis herpetiformis linear lgA disease Fungi Friction Bullous disorders Blisters are classified according to their position in the epidermis. SubCorneal :Stratum Corneum Intraepidermal: Lower levels of the epidermis Sub Epidermal: At the dermo-epidermal junction Blistering Disorders SubCorneal Bullous Impetigo Pustular Psoriasis IntraEpidermal Acute Eczema Herpes simplex/zoster Pemphigus Friction Pemphigoid Thermal Injuries Dystrophic epidermolysis bullosa SubEpidermal Friction Blisters direct mechanical trauma Treatment: avoidance-look at footwear, protective taping and padding, 2 pairs of socks, lubrication. sock design and reduction of blistering Ref.-Herring and Ritchie in JAPMA 1990 and 1993. Required Reading Gawkrodger, D.J. (1992) Dermatology. Edinburgh: Churchill Livingston. Read Chapter on Blistering Disorders and chapter on Keratinization and Blistering Syndromes Hypersensitivity Reactions and the Skin inappropriate or exaggerated response to the degree that tissue damage occurs. 4 Types Type l -immediate Type ll -antibody dependant cytotoxicity Type lll-immune complex disease Type lV-cell mediated or delayed
