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
S u b C o rn eal
B u llo u s Im p etig o
P u stu lar P so riasis
In traE p id erm al
A cu te E czem a
H erp es sim p lex /zo ster
P em p h ig u s
F rictio n
P em p h ig o id
T h erm al In ju ries
D y stro p h ic
ep id erm o ly sis b u llo sa
S u b E p id erm al
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