Dermatology and Infectious Diseases Disorders of Keratinisation Dermatitis Blistering Disorders Immunology

Dermatology and

Infectious Diseases

Disorders of Keratinisation

Dermatitis

Blistering Disorders

Immunology


Overview Psoriasis Icthyosis

Objectives


Disorders of Keratinization

KeratinizationTerminal differentiation of epithelia

– epithelial proteins (Keratin)– Glycoproteins (Cell Envelope)– intercellular lipids


Cause changes in the skin– Dry, Scaly, Thickened, Flaky– Blistering

Cause changes in Mucous membranes, Nails and Hair


Change in Type of Keratin Made




Psoriasis Icthyosis

Disorders of KeratinizationPsoriasis 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 KeratinizationPsoriasis Characterised by hyperproliferation of skin

and inflammation

Etiology– Inherited

• Abnormality of Ca++ metabolism• Genetic Predisposition

– HLA Cw6

– HLA DR7

– HLA B27 (Pustular)

Disorders of KeratinizationPsoriasis

Disorders of KeratinizationPsoriasis Etiology

– Environmental Factors• Stress, Smoking and Alcohol

• Systemic Drugs

• Infection

– Immunological Factors

Psoriasis

Gawkrodger, D.J. (1992) Dermatology. Edinburgh: Churchill Livingston. (1992)

Disorders of KeratinizationPsoriasis 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 KeratinizationPsoriasis 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 KeratinizationPsoriasis Pathology

– Stratum Corneum• contains nuclei

– Stratum granulosum• doesn’t exist

– Stratum Spinosum• expanded• bulbous downward projections• mitosis

Disorders of KeratinizationPsoriasis 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


Psoriasis


Koebner Phenomenon

Required Reading


Psoriasis

Disorders of KeratinisationIcthyoses A variety of hereditary keratinisation

disorders visible scales on the skin Forms include

– autosomal dominant– x-linked– associated with multisystem changes

Disorders of KeratinisationIcthyoses May vary from very mild to very severe

The keratinisation process which is changed varies from condition to condition

Icthyosis


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

DermatitisClassification current classification

unsatisfactory/inconsistent distinctions are often difficult to determine endogenous (internal factors) exogenous (external factors) acute chronic

DermatitisAcute 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

DermatitisChronic

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


DermatitisTypes 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

DermatitisTypes 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 Pemphigoid Epidermolysis bullosa dermatitis

herpetiformis linear lgA disease Fungi Friction

Systemic lupus erythematosis (SLE)

Erythema multiforme Stevens-Johnson

syndrome Bullous impetigo Bullous diabeticorum

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 ImpetigoPustular Psoriasis

IntraEpidermal Acute EczemaHerpes simplex/zosterPemphigusFriction

SubEpidermal PemphigoidThermal InjuriesDystrophicepidermolysis bullosa

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

Documents

Dermatology and Infectious Diseases Disorders of Keratinisation Dermatitis Blistering Disorders Immunology