Intro to General Dermatology Flashcards
Give the basic arrangement of skin structure
Sub cutis
Dermis
Epidermis
What is the function of melanocytes?
Makes melanosomes which are excreted and phagocytose into keranocytes where they sit above the nucleus
What is the function of Langerhans cells?
Process antigens and migrate to lymph nodes to induce an immune response
What are the 5 layers of the epidermis? (inner to outer)
- Stratum basale
- Statum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum
What does the sub cutis-hypodermis consist of?
Fat
What does the dermis consist of?
Collagen and elastin matrix with mucopolysaccharide gel
What cells are found in the dermis?
Fibroblasts
Dermal dendritic cells
Macrophages
How does the epidermis receive its nutrients?
By diffusion NOT blood vessels
Name some components of nail anatomy
Hyponychium Nail plate Lateral nailfold Nail bed Lunula Cuticle Proximal nailfold Proximal nailfold Nail matrix
What are the 3 stages of the hair cycle?
ANAGEN
CATAGEN
TELOGEN
Describe anagen
Active growing phase; 80-90% of hair
Describe catagen
2-3 week phase precedes telogen; growth stops/follicle shrinks; 1-3% of hairs
Describe telogen
Resting phase for 1-4 months; up to 10% of hairs in a normal scalp
What is the condition which involves temporary hair loss following shock, stress or a traumatic event?
Telogen effluvium
Give the 6 important functions of the skin (important exam question)
- Thermoregulation
- Skin immune system
- Barrier
- Sensation
- Vit D synthesis
- Interpersonal communication
What does the barrier function of the skin protect against?
Mechanical, chemical, microorganisms, UV light
What does the barrier function of the skin keep in?
Water + electrolytes, macromolecules
What aspects of interpersonal communication does the skin aid in?
Physical appearance
Smell
Self-identity
How does the skin aid in vit D synthesis?
UV light converts 7-dehydrocholesterol to cholecalciferol
Give the external causes of skin disease
Temp UV Chemical (allergen or irritant) Infection Trauma
Give the internal causes of skin disease
Systemic disease
Genetics
Drugs
Infection
(sidenote lol) Difference between allergen and irritant?
Irritant - reaction no matter who comes into contact with it
Allergen - not the same reaction in everyone
What is photosensitivity?
Immune reaction triggered by sunlight (UVA, UVB, visible light or combo) (sparing under chin is indicative)
Photosensitivity is commonly cause by what?
Medications (antihypertensives, NSAIDs etc)
What are 4 conditions associated with cold injury?
Frostbite
Chilblains
Skin necrosis
Cold urticaria
What is dermatitis artefacta caused by? What is a common presentation of it?
Trauma - psychological reasons
Commonly on non-dominant hand
Patient says ‘I just woke up one day and it looked like that’
Most common trauma is scratching - can lead to…
ulceration
What genetic condition results from 2 copies of the filaggrin gene mutation? (Deficiency)
Icthyosis vulgaris
What is another genetic derm condition where tumours grow along the nervous system?
Neurofibromatosis
Name an autoimmune derm condition
Bullous pemphigoid
Small circumscribed area =
MACULE
Larger circumscribed area =
PATCH
Small raised area =
PAPULE
Larger raised area =
PLAQUE
Small fluid filled =
VESICLE
Large fluid filled =
BULLA
Small pus filled =
PUSTULE
Large pus filled =
ABSCESS
Loss of epidermis =
EROSION
Loss of epidermis and dermis =
ULCER (associated with scarring, contracture, granulation)
What does small usually mean?
Less than 5mm
Try n name the most common skin conditions
Acne Psoriasis Rosacea Skin lesions Urticaria Warts Leg ulcers Scalp/nail disorders Eczema Infections/infestations
What is the cause of eruptive xanthoma which should be treated in order to clear derm pathology?
Hyperlipidaemia
What is acanthosis nigricans associated with?
Insulin resistance
Obesity
Malignancy
What areas are acanthosis nigricans found in?
Flexural areas
What is pretibial myxoedema associated with?
Thyroid disorders - 5% of Graves
Nodules full of mucinous material, also in eyes
What derm investigations are done if bacterial infection suspected?
- Charcoal swab
- MC+S (Microscopy, Culture, Sensitivities)
What are derm investigations for if viral infection suspected?
Viral swab for PCR
Swab vesicle/bulla if vesicular eruption
If systemic illness, can take throat swab
What derm investigations are done if fungal infection suspected?
Skin scraping
Nail clipping
Hair sample
Fungal cultures
Simple way to take skin biopsy?
Punch biopsy (4/5ml of anaesthetic then one stitch after)
Primary investigation for cellulitis?
Blood culture
