Common Skin Disorders & Infections PDF

Common skin disorders and skin infections Dr Jane Setterfield Reader in Dermatology in relation to Oral Disease Consultant Dermatologist Learning Objectives To describe the structure and function of skin To understand the key points in a dermatological history, examination and basic appropriate inve...

Common skin disorders and skin infections Dr Jane Setterfield Reader in Dermatology in relation to Oral Disease Consultant Dermatologist Learning Objectives To describe the structure and function of skin To understand the key points in a dermatological history, examination and basic appropriate investigations To be familiar with common terminology applied to skin lesions To identify the key clinical features of eczema, psoriasis and lichen planus and their treatment To be familiar with the differential diagnosis of pruritus To be able to recognise common skin infections Structure of skin The following two slides demonstrate the structures within the skin Normal human skin Stratum corneum Stratum granulosum Basal layer Dermis Dermal papilla 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. Functions of the skin Protection from the environment Chemical, thermal, physical, UV injury Thermoregulation Neuroreceptor External stimuli Antigen processing Synthesis of vitamin D Cosmetic History taking in a patient with a skin disorder Age, sex occupation History of presenting complaint - symptoms/ initial site/ subsequent involvement Relevant systems review Current/past treatment Past medical history Family history Drug history Allergies Examination should include careful complete skin inspection Remember also ‘Hidden sites’ e.g. scalp, nails, umbilicus, natal cleft mucous membranes oral mucosa eyes nasopharynx ± genitalia Examination (2) site: e.g. localised / generalised/ distribution skin and/or mucous membranes morphology: e.g. mono / polymorphic, blister/ erosion/ scarring background skin: normal/ erythema Erythema is redness of the skin caused by injury or another inflammation-causing condition. When examining the skin it is useful to understand some of the terminology used for skin lesions Flat lesions on skin which are visible as circumscribed areas but are not palpable are: a macule 1cm a plaque = a slightly raised flat topped lesion >1cm diameter This salmon pink plaque with silvery scale is a psoriatic plaque This patient has chronic plaque psoriasis Papule = a circumscribed palpable elevation 1cm This pigmented nodule is a nodular malignant melanoma This patient has a nodular malignant melanoma on her forehead Vesicle = a blister 0.5cm in diameter This patient has angina bullosa haemorrhagica Scale = peeling of the stratum corneum /superficial epidermis This patient has severe eczema 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. Ulcer – full thickness loss of epidermis This lesion is an ulcerated BCC on the lower lip. You can see the characteristic pearly shiny, telangiectatic edge This patient has an ulcerated nodular basal cell carcinoma Scar – permanent change in skin surface/texture This patient has lichen planus in the scalp (lichen planopilaris showing patchy hair loss so called ‘footprints in the snow’) Investigations (1) In order to clarify or confirm a diagnosis the following tests may be needed: Skin swabs/scrapings Bacteriology virology mycology Skin biopsy Histology Culture Immunofluorescence Patch tests suspected Undertaken if a contact allergy is Photo-tests to investigate a possible sensitivity to UV Investigations (2) If a patient is unwell and either infected or in need of systemic therapy, the following blood investigations may be required Haematology: FBC, ESR Biochemistry: U+E, LFT, glucose, CRP Immunology: ANA, DNA, organ specific antibodies Virology: herpes simplex serology Management General measures: assess need for admission e.g. fluid balance, thermoregulation nutrition, infection control Topical: infection - antibacterial agents, candida corticosteroids creams, mouthwash Systemic: prednisolone +/- steroid sparing agents antibiotics Referral: Ophthalmology, Dermatology, ENT Eczema This is a pruritic inflammatory condition associated with dryness and erythema of skin. Scratching results in excoriation and lichenification There are several sub-types of eczema: seborrhoeic Atopic /flexural varicose (Source: Reprinted from Buxton and Morris-Jones, 2009.) discoid Lichen simplex Dermatitis may also be secondary to contact with a substance leading to: Irritant contact e.g.. over hand washing Drug reaction Allergic contact dermatitis Eczema may be secondarily infected with: Staphylococcus aureus (impetiginised eczema) yellow crust and weeping Herpes simplex (eczema herpeticum) Monomorphic lesions Management Avoid soap, shower gel and contact with irritants such as domestic cleaning agents Advise use of: Emollients e.g. soap substitutes, moisturisers Topical steroids Oral antibiotics Antihistamines (sedative) Wet wraps 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 Types Psoriasis vulgaris Guttate Erythrodermic Pustular Psoriasis vulgaris = chronic plaque psoriasis Well-defined salmon pink plaques with silvery scale Psoriasis The scalp and hairline are frequently affected Nail pitting and subungual hyperkeratosis is sometimes present Guttate Psoriasis raindrop size lesions often follows a streptococcal throat infection Generalised pustular psoriasis (a severe but uncommon variant) 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 1-2% population Onset 30-60yrs Flat-topped violaceous papules on skin Predilection for flexor surfaces and lower back Clinical variants Hypertrophic annular plantar Oral – several sub-types Lip genital scalp – lichen planopilaris papular LP hypertrophic LP macular + pigmented Lichen planus results in scarring in some sites Reticular LP Oral lichen planus Desquamative gingivitis Lichen planus - treatment Topical emollients topical steroids (check candida count orally) Systemic Prednisolone azathioprine/ mycophenolate methotrexate Pruritus Xerosis Dietary Endocrine Inflammatory Autoimmune Infective Infestation Parasitic Neoplastic dry skin iron deficiency anaemia thyroid disorders, diabetes mellitus eczema, urticaria lichen planus, dermatitis herpetiformis chicken pox scabies cutaneous larva migrans cutaneous T cell lymphoma, myeloproliferative, lymphoma Viral infections: varicella Chicken pox Shingles – unilalateral - dermatomal Herpes simplex Molluscum contagiosum (pox virus) Warts (human papilloma virus) Bacterial infections Staphylococcus aureus/ streptococcal infections Impetigo cellulitis paronychia Fungal infections Infections include Trichophyton species Summary In this lecture we have discussed the structure and function of the skin Key aspects of history/examination Morphology of skin lesions the key clinical features /treatment of eczema, psoriasis and lichen planus the differential diagnosis of pruritus Common skin infections Thank you