Introduction to Dermatology Flashcards
What is the structure and function of the subcutaneous layer of skin?
Structure: Fat energy store
Function: Insultation
Structure: Fibrous bands
Function: Anchor skin to fascia
What is the structure of the dermis?
Collagen and elastin matrix with mucopolysaccharide gel also fibroblasts, dermal dendritis cells and macrophages
What are the three cell types found in the epidermis?
Epidermis: Keratinocytes (majority of cells), melanocytes and langerhans cells
What is the function of melanocytes?
Makes melanosomes (collections of melanin)
What is the function of langerhans cells?
Process antigens and migrate to lymph nodes to induce an immune response
What are the layers of the skin?
What are the stages of the hair cycle?
Anagen - growing phase
Catagen - growth stops for 2-3 weeks, hair follicle shrinks
Telogen - Resting phase for 1-4 months
What are the functions of skin?
•Thermoregulation
–Insulation, Heat transfer
•Skin immune system
–Innate and Adaptive functions
•Barrier
–Protects against Mechanical, Chemical, microorganisms, Ultraviolet light
–Keeps in water and Electrolytes, Macromolecules
•Sensation
–Temperature, touch and pain
•Vitamin D synthesis
–UV light converts 7-dehydrocholesterol to cholecalciferol
•Interpersonal Communication
–Physical appearance, smell, self -identity
What are the causes of skin disease?
•External
–Temperature, UV, chemical (allergen or irritant), infection, trauma
(photosensitivity, cold injury (frost bite, utricaria, chilblains)
•Internal
–Systemic disease, genetics, drugs, infection, Autoimmune (bullous pemphigoid)
Describe photosensitivity
Commonly caused by medications (NSAIDS, bendroflumethiazide)
Exposed sites are affected - may be sensitive to visible light or UV light
What is utricaria?
Usually seen as a wheel on the skin
Urticaria – mast cells degranulate (spontaneous is most common) – nettle sting type reaction – can happen as a result of pressure, cold weather or even water
Is dermatitis artefacta caused by internal or external reasons?
External:
Dermatitis artefacta is a condition in which skin lesions are solely produced or inflicted by the patient’s own actions. This usually occurs as a result or manifestation of a psychological problem. It could be a form of emotional release in situations of distress or part of an attention seeking behaviour.
What words are used to describe the size of the skin lesion?
Macule Small circumscribed area
Patch Larger circumscribed area
(small means less than 5 mm)
What words are used to describe if the skin lesion is raised or not raised?
Papule - small raised area
Plaque - large raised area
What words are used to describe if the skin lesion is fluid filled?
Vesicle - small fluid filled
Bulla - large fluid filled
What words are used to describe if the skin lesion is pus filled?
Pustule - small pus filled
Abscess - large pus filled
What words are used to describe the depth of the skin lesions?
Erosion - Loss of Epidermis
Ulcer - Loss of Epidermis and dermis
What are the most common skin conditions?
Some conditions have cutaneous signs:
Erythema Nodosum
Sarcoidosis
Vasculitis
Malignancy
Auto-immune conditions
What skin condition can happen as a result of abnormal lipid metabolism?
Eruptive xanthoma - hyperlipidaemia
What is acanthosis nigricans assoicated with?
Insulin resistance
Obesity
Malignancy
What are the features of acanthosis nigricans?
Hyperkeratosis
Hyperpigmentation
Papules
Velvety appearance
Flexural distribution
What are the skin features of thyroid skin disease?
Myxoedema - swelling of the skin and underlying tissues - gives skin a waxy appearance - typical of patients with an underactive thyroid gland
Pretibial myxoedema
Mucinosis (fibroblasats produce abnormally large amounts of acid mucopolysaccharides) - causing eye disease
Other eye diseases are also common in thyroid skin disease
What are the investiagations in dermatology?
Charcoal swab - you can’t swab for cellulitis - the investigation for cellulitis is blood culture
MC and S
Suspected viral infection - viral swab for PCR ( you can swab vesicles, bulla (ruptured) or throat)
Fungal infection (skin scraping, nail clipping, hair sample, fungal cultures)
Punch biopsy
