Common skin disorders and skin infections

red

stratum corneum

orange

stratum granulosum

yellow

basal layer

green

dermis

blue

dermal papilla

skin adnexae

hair, sebaceous/sweat glands

The skin is the largest organ in the body. In addition to skin adnexae (hair, sebaceous/sweat glands), there is a complex vascular network which allows the skin to shunt blood to the surface to dissipate heat or retain blood flow deeper in the dermis.

• flexural sites - neck/groin →thin epidermis → be careful of treatments you use

• thicker sites - palms and soles

Functions of the skin 6

1. Protection from the environment Chemical, thermal, physical, UV injury

2. Thermoregulation

3. Neuroreceptor → External stimuli - lips, genatalia, mouth

4. Antigen processing (Langerhans cells) → WHEN THIS GOES WRONG → contact sensitivity

5. Synthesis of vitamin D

6. Cosmetic

History taking in a patient with a skin disorder - what should you ask about? 8

1. Age, sex occupation

2. History of presenting complaint - symptoms/ initial site/ subsequent involvement

3. Relevant systems review

4. Current/past treatment

5. Past medical history

6. Family history

7. Drug history

8. Allergies

Examination - skin inspection

• should include careful complete skin inspection

1. ‘Hidden sites’ e.g. scalp, nails, umbilicus, natal cleft

2. mucous membranes oral mucosa, eyes, nasopharynx ± genitalia

what factors should you consider when taking a skin inspection ?

1. site: e.g. localised / generalised/ distribution skin and/or mucous membranes

2. morphology: e.g. mono / polymorphic, blister/ erosion/ scarring

3. background skin: normal/ erythema

palpable

cannot be touched - raised

Flat lesions on skin which are visible as circumscribed areas but are not palpable are:

macule or patch

how do you distinguish a macule from a patch?

a macule <1cm a patch >1cm

a slightly raised flat topped lesion >1cm diameter

plaque

This patient has chronic plaque psoriasis

a circumscribed palpable elevation <1cm

• a papule

• These flat topped papules are lichen planus

a palpable elevation >1cm

• nodule

• This patient has a nodular malignant melanoma on her forehead

a blister <0.5cm diameter is known as a …

• vesicle

• This patient has pompholyx eczema on the thenar eminence (palm)

• monomorphic lesions

a blister >0.5cm in diameter is known as a …

• bulla

• This patient has angina bullosa haemorrhagica

peeling of the stratum corneum /superficial epidermis

• a scale

• This patient has severe eczema

lichenification vs excoriation

• Lichenification = thickening from scratching is visible here in the popliteal fossa

• Excoriation = a shallow breach in the surface from scratching often with a haemorrhagic crust

• This patient has severe atopic eczema.

full thickness loss of epidermis

• ulcer

• This patient has an ulcerated nodular basal cell carcinoma

• raised margin, looks see through (opalescent)

permanent change in skin surface/texture

scar

This patient has lichen planus in the scalp (lichen planopilaris showing patchy hair loss so called ‘footprints in the snow’)

In order to clarify or confirm a diagnosis the following tests may be needed: 4 investigations

1. Skin swabs/scrapings → Bacteriology, virology, mycology

2. Skin biopsy → Histology, Culture, Immunofluorescence

3. Patch tests → Undertaken if a contact allergy is suspected

4. Photo-tests → to investigate a possible sensitivity to UV

If a patient is unwell and either infected or in need of systemic therapy, the following blood investigations may be required - investigations 4

1. Haematology: FBC, ESR

2. Biochemistry: U+E, LFT, glucose, CRP

3. Immunology: ANA, DNA (
   lupus), organ specific antibodies (thyroid/liver)

4. Virology: herpes simplex serology

management - general measures

assess need for admission : e.g. fluid balance, thermoregulation nutrition, infection control

management - topical

infection - antibacterial agents, candida corticosteroids creams, mouthwash

management - systemic

prednisolone +/- steroid sparing agents antibiotics

management - referrals

Ophthalmology, Dermatology, ENT

what is Eczema?

This is a pruritic inflammatory condition associated with dryness and erythema of skin. Scratching results in excoriation and lichenification

is aka dermatitis

image - flexural eczema

eczema scratching results in…

excoriation and lichenification

There are several sub-types of eczema: list them

1. Atopic /flexural - young

2. varicose - old, venous incompetence

3. seborrhoeic - centre of face and the scalp , anogenital skin

4. discoid - coin shaped

5. Lichen simplex

what type of eczema is this?

Atopic /flexural

what type of eczema is this?

varicose

what type of eczema is this?

seborrhoeic

what type of eczema is this?

what type of eczema is this?

lichen simplex

Dermatitis may also be secondary to contact with a substance 2

1. Irritant contact e.g.. over hand washing - can affect anyone

2. Allergic contact dermatitis - only found in patients who have a hypersensitivity to a specific allergen

Eczema may be secondarily infected with: 2

1. Staphylococcus aureus (impetiginised eczema) yellow crust and weeping (not impetigo)

2. Herpes simplex (eczema herpeticum) Monomorphic lesions - eye can be permanently affected - ophthalmologist needs to be involved

eczema - Management

Avoid soap, shower gel and contact with irritants such as domestic cleaning agents

Advise use of:

1. Emollients e.g. soap substitutes, moisturisers

2. Topical steroids

3. Oral antibiotics

4. Antihistamines (sedative)

5. Wet wraps

6. Acyclovir if suspect herpes simplex (eczema herpeticum)

Psoriasis – clinical features

• 2% prevalence.

• Strong family history

• Symmetrical well-defined red plaques with thick silvery scale

• Elbows and knees common sites

• Lasts for many years - increases in severity

Psoriasis – types

1. Psoriasis vulgaris - common

2. Guttate - tear drops → follows a throat infection

3. Erythrodermic - red in widespread distribution

4. Pustular - needs to be hospitalised

• Psoriasis vulgaris = chronic plaque psoriasis

• Well-defined salmon pink plaques with silvery scale

psoriasis - scalp and nails

• The scalp and hairline are frequently affected

• Nail pitting and subungual hyperkeratosis is sometimes present → due to plaques under the nails

• guttate psoriasis

• raindrop size lesions often follows a streptococcal throat infection

Generalised pustular psoriasis (a severe but uncommon variant) - flexural regions

Psoriasis - treatment

• Emollients/ bath oils

• Vitamin D analogues – e.g. calcipotriol

• Tar preparations

• Topical steroids

• Dithranol

• UVB, PUVA

• Systemic – acitretin, methotrexate, cyclosporin, biologics

Lichen planus

• Unknown aetiology - perhaps autoimmune

• 1-2% population

• Onset 30-60yrs

• Flat-topped violaceous papules on skin

• Predilection for flexor surfaces and lower back

Lichen planus Clinical variants

• Hypertrophic →thick plaques

• annular → ring

• plantar → flat tops

• Oral – several sub-types

• Lip

• genital

• scalp – lichen planopilaris

• most common around flexture surfaces

• a range of presentations

Lichen planus results in scarring in some sites

Oral lichen planus

Desquamative gingivitis may be caused by LP

Lichen planus - treatment - topical

• emollients

• topical steroids (check candida count orally - can be a secondary infection)

Lichen planus - treatment -systemic

• Prednisolone

• azathioprine/ mycophenolate

• methotrexate

(immunosuppressants)

Pruritus

itching

causes of Pruritus 9

1. Xerosis → dry skin

2. Dietary → iron deficiency anaemia

3. Endocrine → thyroid disorders, diabetes mellitus

4. Inflammatory → eczema, urticaria

5. Autoimmune → lichen planus, dermatitis herpetiformis

6. Infective → chicken pox

7. Infestation → scabies

8. Parasitic →cutaneous larva migrans

9. Neoplastic → cutaneous T cell lymphoma, myeloproliferative, lymphoma

Viral infections: varicella

chicken pox (polymorphic)and shingles

how can you describe shingles?

unilateral and dermatomal

Herpes simplex

Molluscum contagiosum (pox virus)

umbilication

small, central depression on papules

Warts (human papilloma virus)

Bacterial infections Staphylococcus aureus/ streptococcal infections 3

1. Impetigo

2. cellulitis

3. paronychia

Fungal infections

Infections include Trichophyton species