Dermatology Flashcards
What is the function of skin?
Anatomical barrier
Heat regulation
Sensory input
Storage for lipids and water
Drug absorption and waste excretion
What is commensalism flora?
Normally colonisation that inhibits pathogens in healthy hosts (staph and candida)
What is the cause of oily skin?
More secretion from sebaceous glands
More bacteria colonisation - risk of pore blockage and spots
What are blackheads?
Comedones - build up of keratin and sebum which block pores and oxidise giving black appearance
What is Furuncles?
Bacterial infection of the skin
Staph aureus
Pockets filled with pus- red/ swollen/ painful
Foliculitis (in hair follicle)
Drain pus (antibiotics not always required)
What is Acne?
Bacterial infection of the skin affecting 80% teenagers
Caused by follicular sensitivity to testosterone (increase around puberty, build up of comedones)
Overgrowth can lead to infection and cyst formation (scarring if cyst rupture)
What are some complications of acne?
Made worse by contraceptive pills, greasy skin cleansers, systemic steroid treatment, anticonvulsants.
How is acne managed?
Reduce excess oil (gentle soap)
Antibacterial agents- benzoyl peroxide/ retinoids/ antibiotic lotions
If local treatments fail- systemic treatment:
Antibiotics- tetracycline
Retinoids (isotertinoin)
Hormone manipulation
What is erysipelas?
Strep pyogenes infection
Defined, sharp, raised border which may blister and peel
Associated with systemic symptoms- fever/ rigor
How is erysipelas managed?
Systemic antibiotics (oral or IV) as this can progress to necrotising fasciitis or septic shock
What is impetigo?
Highly infectious skin disease caused by staph/ strep
Crusty red blister
Associated with eczema
Treated with topical antibiotics
What are examples of viral skin infections?
Herpes simplex
Shingles
Molluscum contagiosum
Warts
What are examples of herpes virus infections
Herpes simplex (peri oral or genital)
Shingles (herpes zoster)
Roseola (HHV6)
Kaposi’s sarcoma (HHV8)
What is the aetiology of herpes simplex infections and how is it treated
Affects a single dermatome
Activated by trauma
Treated with aciclovir
What is molluscum contagiosum?
Viral infection caused by MCV (pox virus)
Clusters of small papules in warm/ moist areas
Usually in small children and resolves in 1-2 year
Troublesome in children with atopic eczema
Extensive in adults if HIV infection
What virus are warts caused by, how are they spread and what is the treatment?
Human Papilloma Virus (HPV)
- types 1-3 cause most warts
- types 16 and 18 cause cervical cancer
Contact spread
Treat by keratolysis, cryosurgery, excision (most resolve spontaneously if immune competent)
What are examples of fungal infections?
Athletes for (tines pedis)
Nail infections (onycholysis)
Ringworm
Intertrigo
Pityriasis versicolor
What is athletes foot and its treatment?
Mixed fungal and bacterial infection affecting feet (between toes) or groin.
Causes scaling and sogginess of the skin.
Treat with antifungal/ antibacterial cream eg miconazole
What is onycholysis?
Nail bed fungal infection (tinea unguium) where the nail bed becomes malformed/ thick/ crumbly
What is ringworm?
Fungal infection which can affect groin (tinea cruris), body (tinea corporis) and scalp (tinea capitis)
What is intertrigo and its treatment?
Fungal infection sue to chafing in moist body folds (eg under breasts, armpits, inner thighs)
Treat with topical antifungal cream - miconazole or clotrimazole
What is pityriasis versicolor and its treatment?
Caused by pityrosporum orbiculare resulting in patchy skin pigmentation (pale red/ brown)
Treat with topical (ketocanazole in wash/ shampoo) or systemic (itraconazole) antifungals.
What is scabies?
Infection of scabies mite from skin to skin contact
What is the presentation of scabies infection?
Burrows appear on skin (in folds between fingers and on wrists)
Itching most severe at night on trunk/ limbs
Rash appears on trunk and limbs (may get secondary impetigo)
Rash and itch are an allergy and can persist long after infestation is gone
In scabies, how many mites infect the host?
10-12, lay 3 eggs a day
What is the treatment of scabies?
Chemical insecticides - eg benzoyl benzoate
Apply to whole body from chin down (including under nails)
Treat all close contacts whether obviously infected or not
What are the types of lice, how are they transmitted and what is the treatment?
Head
Pubic
Body
Transmitted by close contact with an infected individual/ shared items
Treat head lice by removing nits (eggs cemented to hair) with fine tooth comb
Treat body lice by personal and clothing hygiene - hot water washing and drying
Treat pubic lice with chemical insecticides - permethrin, malathion, phenothrin.
What is eczema?
Inflammation of the skin- becomes itchy/ dry/ flaky
Can be atopic (most common) or contact
Usually affects flexor surfaces of skin/ trunk
Other types:
- seborrhoeic (scalp and eyelashes)
- discoid
- gravitational
What is atopic eczema?
FH
Associated with other atopic conditions eg asthma/ hay fever
What is contact eczema?
Adult onset - contact with allergen eg perfume/ detergent/ soap.
Describe the management of eczema?
Cotton clothing
Emollients - oily and prevent drying of the irritated skin, apply after bathing to trap moisture
Corticosteroid- remove the inflammation and allow skin to return to normal
What is occupational (contact) dermatitis and its treatment?
Reaction to environmental agent (usually results in intense rash which may blister).
Immediate/ up to 72 hours after exposure
Treat by removing source/ topical steroid
What is psoriasis?
Inflammatory skin condition with unknown cause
Dysregulated epidermal proliferation (new cells produced faster than old cells are lost, skin surface thickens) - red, scaly patches
Affects extensor surfaces of limbs and trunk
Can be associated with severe forms of arthritis
What is the treatment of psoriasis?
Initially topical- emollients, steroids, vit A derivatives, PUVA (light therapy)
Then systemic treatment - reduce cell turnover with methotrexate/ cyclosporin
Why do some blistering conditions affect the mouth and genitals?
Skin and oral/ genital mucosa may share many common antigens and epitopes
What is pemphigoid?
Sub epithelial antibody attack causing thick walls blisters
Manage with immunosuppressants
What is pemphigus
Immunological blistering condition affecting mucosa and skin (usually oral lesion before skin)
Intra-epithelial blister
Surface lost easily
Fatal without treatment
What is epidermolysis bullosa?
Group of conditions (some mild with later presentation, some fatal with immediate presentation after birth)
- severity determined by epitopes involved
