Dermatology Flashcards
What is basal cell carcinoma?
A common neoplasm, related to exposure to sunlight-clinically presents as a pearly white papulo-nodule or firm plaque
What is the aetiology of basal cell carcinoma?
Repetitive and frequent sun exposure, as ultraviolet (UV) radiation induces DNA damage in keratinocytes
What is the epidemiology of basal cell carcinoma?
The most common malignancy of the skin in fair-skinned adults in the US, Australia, and Europe and its incidence is increasing
The incidence of BCC has been shown to increase markedly after the age of 40 years (incidence in younger people is steadily rising)
What are the presenting symptoms of basal cell carcinoma?
Pearly papules/plaques
Non-healing scabs
What are the signs of basal cell carcinoma on physical examination?
Plaques, nodules and tumours:
- pearly appearance
- rolled borders
- small crusts, non-healing
- associated Telangiectasis (tiny thread like blood vessels)
What are the appropriate investigations for basal cell carcinoma?
*Biopsy for dermatohistopathology:
(diagnosis of a cancer is histological)
-growth of nest(s) of varying size and shape
-either tightly associated with epidermis or follicular opening
-neoplasm composed of basophilic (blue) hyperchromatic cells
-stroma surrounding BCC is hypercellular, fibrous
-separation artefact between nests of neoplastic cells and the stroma (so-called stroma-epithelium split)
What is a burns injury?
A very common injury predominantly to skin and superficial tissues caused by heat from hot liquids, flame or contact with hot objects
How is the severity of burns injuries assessed?
- Burn size (% of total body surface area)
- Depth ( first to fourth degree)
What symptoms and signs would be seen on physical examination for a burns injury?
Erythema Dry/ wet and painful Dry and lacking of physical sensation (insensate) Cellulitis If face affected- clouded cornea
What are the risk factors for burn injuries?
Young children
Age > 60 years
What are the investigations for burn injuries?
FBC: Hb, Platelets, WCC, CRP, ESR
ABG: assessment of lungs/ inhalation injury
Wound biopsy and histology
What is candidiasis of the skin?
When Candida colonises on the skin causing an infection. Also known as cutaneous candidiasis
What is the aetiology of candidiasis of the skin?
- Candida is a yeast-like fungus which is part of the normal commensal flora of the human gastrointestinal tract and the vagina
- Candida albicans is the most common species and is responsible for over half of candidal skin infections
- It is not part of the normal skin flora, but there may be transient colonization of fingers or body folds
- Usually asymptomatic but where mucosal barriers are disrupted or if the host’s defences are lowered, it can cause infections
What is the epidemiology of candidiasis of the skin?
Candidiasis is common, being at extreme ages is a risk factor due to immature or weakened immunity
What are the risk factors for candidiasis of the skin?
More likely to occur where skin rubs on skin (such as between skin folds in an obese person) and where heat and moisture lead to maceration and inflammation
Other RF:
-Immunocompromised (HIV infection, chemotherapy, immunosuppressive drugs)
-General debility, for example from cancer or malnutrition
-Recent or concurrent use of drugs that promote candidal growth, particularly broad-spectrum antibiotics and inhaled or oral corticosteroids
-Diseases in which the barrier function of the skin is disturbed (such as psoriasis and seborrhoeic eczema).
-Endocrine disorders: Diabetes mellitus and Cushing’s syndrome
-**Iron deficiency anaemia — iron is the most common deficient essential micronutrient implicated in the colonization of Candida, as iron deficiency diminishes the fungistatic action of transferrin and other iron-dependant enzymes
-High-oestrogen contraceptive pill or pregnancy
-Poor hygiene
What are the presenting symptoms of candidiasis of the skin?
Rash-often causes redness and intense itching
Blisters and pustules may also occur
The rash is most likely to develop in the folds of the skin:
-armpits
-the groin
-between the fingers
-under the breasts
Candida can also cause infections in the nails, edges of the nails, and corners of the mouth
What are the signs of candidiasis of the skin on physical examination?
-Thin-walled pustules with a red base may be present
-Scales may accumulate, producing a white-yellow, curd-like substance over the infected area
In flexural areas (intertrigo), the skin fold is typically red and moist
-As the condition develops: a typical fringed, irregular edge and pustular or papular satellite lesions may be present
-If the web spaces of the toes or fingers are involved, marked maceration with a thick, horny layer is usually prominent
What are the appropriate investigations for candidiasis of the skin?
Investigations are not usually necessary, but may be required to exclude a differential diagnosis or an underlying condition (such as diabetes or anaemia), especially in people with widespread or recurrent infection
Swabs are not routinely recommended. However, standard bacteriology swabs for microscopy and culture may be required if:
-Secondary bacterial infection is suspected
-The person is immunocompromised
-The diagnosis is uncertain
What is Cellulitis?
An acute spreading infection of the skin with visually indistinct borders that principally involves the dermis and subcutaneous tissue
Characterised by: erythema, oedema, warmth, and tenderness, and commonly occurs in an extremity
What is Cellulitis usually characterised by?
Erythema Oedema Warmth Tenderness Commonly occurs in an extremity
What is Erysipelas?
A distinct form of superficial cellulitis with notable lymphatic involvement and is raised, sharply demarcating it from uninvolved skin
What is the aetiology of Cellulitis?
Cellulitis develops when micro-organisms gain entry to the dermal and subcutaneous tissues via disruptions in the cutaneous barrier
The most common causative agents are:
-Beta-haemolytic streptococci
-Staphylococcus aureus
What is the epidemiology of Cellulitis?
Cellulitis is a common condition Main risk factors are: -skin break -poor hygiene -poor vascularization of tissue (e.g. diabetes mellitus)
What are the presenting symptoms of Cellulitis?
There may be history of a cut, scratch or injury
Skin discomfort
Periorbital: Painful swollen red skin around eye
Orbital cellulitis: Painful or limited eye movements, visual impairment
What are the signs of Cellulitis on physical examination?
Lesion: -Erythema -Oedema -Warm tender indistinct margins *Pyrexia may signify systemic spread Exclude abscess: Test for fluid thrill or fluctuation- aspirate if pus suspected Periorbital: -Swollen eyelids -Conjunctival injection Orbital cellulitis: -Proptosis (protrusion of the eyeball) -Impaired acuity and eye movement Test for relative afferent pupillary defect, visual acuity and colour vision
What are the appropriate investigations for Cellulitis?
Bloods: WCC, blood culture
Discharge: Culture and sensitivity
Aspiration: As it is often non-purulent, it is not usually necessary
CT/MRI scan: When orbital cellulitis is suspected (to assess the posterior spread of infection)
What is the management of Cellulitis?
Medical:
-Oral penicillins (e.g. flucloxacillin, benzylpenicillin, coamoxiclav)
-Tetracyclines are effective in most community acquired cases
-In the hospital- intravenous use may be necessary
Surgical:
-Orbital decompression may be necessary in orbital cellulitis(emergency)
Abscess: Abscesses can be aspirated, incised and drained or excised completely
What are the complications of Cellulitis?
Sloughing (shedding) of overlying skin Localized tissue damage In orbital cellulitis, there may be permanent vision loss and spread to brain Abscess formation Meningitis Cavernous sinus thrombosis
What is the prognosis of Cellulitis?
Good with treatment
What is Eczema?
An inflammatory skin reaction to endogenous or exogenous agents characterised by dry, pruritic skin with a chronic relapsing course
What is the aetiology of Eczema?
Numerous varieties caused by a diversity of triggers
- Atopic: Impaired epidermal barrier function or immune function disorder
- Contact: Type IV delayed hypersensitivity to allergen (e.g. nickel, chromate, perfumes, latex and plants)
- Discoid
- Dyshidrotic
- Herpeticum
- Seborrhoeic: Pityrosporum yeast seems to have a central role
What is the epidemiology of Eczema?
Contact: Prevalence 4 %
Atopic: Onset is commonly in the first year of life, childhood incidence 10–20 %
What are the presenting symptoms of Eczema?
Itching (can be severe), heat, tenderness, redness, weeping, crusting
Enquire into occupational exposures or irritants used at home (e.g. bleach) and into family/personal history of atopy (e.g. asthma, hay fever, rhinitis)
What are the signs of Eczema on physical examination?
Acute:
-Poorly demarcated erythematous oedematous dry scaling patches
-Atopic: Particularly affects face and flexures (inside elbow and knee)
-Papules, vesicles with exudation and crusting, excoriation marks
Chronic:
-Thickened epidermis
-Skin lichenification
-Fissures
-Change in pigmentation
Seborrhoeic: Yellow greasy scales on erythematous plaques, particularly in the nasolabial folds, eyebrows, scalp and presternal area
What are the appropriate investigations for Eczema?
Primarily clinical
Contact:
-Skin patch testing: Disc containing postulated allergen is diluted and applied to back for 48 h
-Positive if allergen induces a red raised lesion
Atopic:
-Laboratory testing, including IgE levels, are not used routinely and are not currently recommended
-Swab for infected lesions (bacteria, fungi and viruses)
What are Epidermoid and pilar cysts (sebaceous cysts)?
Benign small bumps beneath the skin
They can appear anywhere on the skin, but are most common on the face, neck and trunk
Two of the most common types of cysts
What is the aetiology of Epidermoid and pilar cysts?
Most form when cells from the epidermis move deeper into the skin and multiply rather than slough off
Sometimes the cysts form due to irritation or injury of the skin or the most superficial portion of a hair follicle.
The epidermal cells form the walls of the cyst and then secrete the protein keratin into the interior
The keratin is the thick, yellow substance that sometimes drains from the cyst
This abnormal growth of cells may be due to a damaged hair follicle or oil gland in your skin
Cysts that form around hair follicles are Pilar cysts
*These cysts used to be called sebaceous cysts but this term is no longer correct, as the origin of these cysts is not from the sebaceous glands in the skin, as was once thought
What is the epidemiology of Epidermoid and pilar cysts?
Epidermoid cysts: most common in young and middle-aged adults (develop on the face, neck, chest, upper back)
Pilar cysts: most common in middle-aged women and develop most commonly on the scalp
What are the presenting symptoms of Epidermoid and pilar cysts?
A small, round bump under the skin, usually on the face, neck or trunk
A tiny blackhead plugging the central opening of the cyst
A thick, yellow material that sometimes drains from the cyst
Redness, swelling and tenderness in the area, if inflamed or infected
What are the appropriate investigations for Epidermoid and pilar cysts?
The diagnosis of an epidermoid or pilar cyst is usually clinical
However, if suspicious the tissue can be excised and submitted for histology
What is Erythema multiforme?
An acute hypersensitivity reaction ( inflammatory condition) of the skin and mucous membranes, which is often self-limiting but often relapsing
What is the pathology of Erythema multiforme?
Degeneration of basal epidermal cells and development of vesicles between the cells and the underlying basement membrane
Lymphocytic infiltrate is seen around the blood vessels and at the dermal – epidermal junction
Immune complex deposition is variable and non-specific
Precipitating factor is only identified in only 50 % of cases
What is the aetiology of Erythema multiforme?
Drugs: Sulphonamides, penicillin, phenytoin, barbiturates Infection: -Viral: HSV, EBV, coxsackie, adenovirus -Bacterial: Mycoplasma pneumoniae, Chlamydiae -Fungal: Histoplasmosis Inflammatory: -Rheumatoid arthritis -SLE -Sarcoidosis -Ulcerative colitis -Systemic vasculitis Malignancy: -Lymphomas -Leukaemia -Myeloma Radiotherapy
What is the epidemiology of Erythema multiforme?
Any age group, but most commonly children and young adults
M:F: 2:1
