Dermatology Flashcards
What diseases are linked to erythema nodosum?
Strep infection TB Leprosy Glandular fever Histoplasmosis Coccidioidomycosis Lymphoma Sarcoidosis Pregnancy, the OCP Reaction to sulphonamides IBD
What is pemphigus?
A superficial blistering disorder where within the epidermis there is a split. The blisters are very fragile and generally leave widespread erosions.
What causes pemphigus?
Autoimmune against desmosomal components. Can be brought on by drugs (ACEi, NSAIDs, phenobarbital, L-dopa). Can be associated with carcinoma, lymphoma, thymoma, SLE
What is pemphigoid?
A deep blistering disorder where there is a split at the basement membrane
What causes pemphigoid?
Infections, insect bites, drugs (ACEi), dermatitis herpetiforms, friction, discoid eczema, low Zn, autoimmune blistering disorders
Describe the differences between urticarial, erythema multiform, steven johnsons syndrome and toxic epidermal necrolysis:
URTICARIA: Local increase in permeability of the capillaries and small venules, resulting in transient itchy rash. The rash can change location day to day.
ERYTHEMA MULTIFORM: Acute self limiting inflammatory condition precipitated by HSV or drugs. Target lesions and blisters with limited mucosal involvement - usually on extensor surfaces, hands and soles
STEVEN JOHNSON’S SYNDROME: Major erythema multiform. Drug reaction with necrosis at 2 mucosal sites. Mucosa much more involved than the skin. ~ 10% of skin involved, it is blistered and eroded.
TOXIC EPIDERMAL NECROLYSIS: Major major erythema multiform. Full thickness involvement of the epidermis, it separates from the dermis.
What is a macule compared to a plaque?
Macule = An area of change in the skin that you can see but if you close your eyes you cannot feel. Plaque = area of change that is raised you can see and see it. It is a flat textural change
What is a papule compared to a nodule?
Papule = a bump that is 1cm
What is an erosion compared to an ulcer?
An erosion is the loss of superficial epidermis An ulcer is where the whole layer of epidermis has been lost, it can include dermis and sub cut fat.
What is desquamation?
Where the skin peels off, the underlying skin is usually normal
What are the functions of the skin?
Physical barrier Thermoregulation Protects against UV light Immunological interface Sensory/ endocrine function Communication
What are the different layers of the skin?
EPIDERMIS: Stratified epithelium of ectoderm orgin Arises from basal keratinocytes (where the melanocytes are found) From bottom up –> basal cells migrate into the granular layer which then loose their nuclei when they reach the stratum corneum layer
What are the different layers of the skin?
EPIDERMIS: Stratified epithelium of ectoderm orgin Arises from basal keratinocytes (where the melanocytes and Merckels cells are found) From bottom up –> basal cells migrate into the granular layer which then loose their nuclei when they reach the stratum corneum layer BASEMENT MEMBRANE ZONE Holds the skin together Keep epiderms attached to the dermis DERMIS Mesodermal origin Contains blood vessels, nerves, muscles and glands with hair follicles. Eccrine glands are found in all skin, Apocrine glands are only found in axilla, anogential and scalp.
How would you describe classic atopic childhood eczema?
Papules and vesicles on an erythematous base. Classically on the flexoral aspects, anti-cubital fossa and behind the knees. Poorly defined lesions with signs or excoriation and lichenification. In children can have classic atopic facies: Morgan Dennie Folds (creases under the eyes) Eczema on cheeks (spares the top of nose) mouth breathing
How is infantile eczema different from classical eczema?
It widely effects their face and is diffuse in a seborrhoeic pattern.
What is pomphyolyx eczema?
A vesicular hand eczema that has tapioca like blisters present
What are the two categories for the aeitology beind eczema?
EXOGENOUS: result of external factors
Contact dermatitis - type IV reaction
Nappy dermatitis
Infective eczema
Photosensitive
ENDOGENOUS: result of something internal
Atopic
Seborrhoic -type IV reaction to yeast
Pompholyx
Venous - due to stasis of blood in legs
What is thought to be the pathophysiology behind eczema?
The skin barrier looses its smooth protective function, ? loss of the protein flaggin
How do you treat eczema?
Mild - EMOLLIENTS, only use mild potency steriod as rescue
Moderate - EMOLLIENTS, moderate topical steriod, topical calcineurin inhibitors (tacrolimus) bandages
Severe - EMOLLIENTS, potent topical steriods, topical tacrolimus, bandages, phototherapy, systemic therapy.
What is the order of strength of the topical steriods?
Hydrocortisone strength of 1
Eumovate
Betnovate strength of 200
Dermovate strength of 600
What infections most commonly infect eczema?
Pathogens that are present on the skin:
Staph aures (golden flacking)
HSV and VZV
What causes eczema herpeticum?
Disseminated HSV in eczema
What is seborrhoeic dermatitis?
A type IV delayed reaction to a yeast that is naturally occuring on the skin.
It is found more often in men and people who are immunosupressed.
It is found in the scalp and in the eyebrows, and is recurrent.
Treat with antifungal shampoo or cream
What is psoriasis?
A chronic inflammatory skin condition. It results due to increased proliferation of the cells, they have a shortened cell cycle - there is increased keratincytes.
The process is T cell mediated
What are some of the triggers of psoriasis?
Stress, infection (espc strep), skin trauma, drugs (lithium, NSAIDs, B blockers, anitmalarials), alcohol, smoking and climate.
These can be triggers for the first episode and then also for subsequent epsiodes
What are the skin and extra skin signs of psorasis?
Skin: Well demarcated salmon pink plaques, found on the extensor surfaces, sacrum.
Nail changes: pitting, onchlysis and sublingual hyperkeratosis.
Some patients have features consistent of seronegative arthropathy: rheumatoid like arthritis, psoritatic arthritis, ankylosing spondylitis, osteo like arthritis, etc.
What are the different subtypes of psorasis?
Guttate - small lesions, usually young men after a strep infection
Palmo-plantar pustular psoriasis - effects hands and feet and is associated with sterile pustules.
Erythroderma - generalised condition with hot red skin, assocaited with fever, high WCC and dehydration
How is psorasis managed?
Education - remove triggers
Topical - Emollients, steriods, tacrolimus, topical vitamin D analogues (calcipotriol), tar, dithranol
Phototherapy
Systemic - methotrexate, cylosporins, retinoids (vitamin A analogues), anti TNF
Impetigo:
The bacteria?
The classic presentation?
Other presentations?
Treatment?
Most commonly Staph Aureus
Lesions are most common in children. Well defined, on the face with golden honey crusts on an erythematous base.
Can present as Bullou impetigo, with blisters
Initally treated with topical antibiotics and then oral flucoxillin in severe
If a patient has imetigo and then has areas of red desquamation what would you worry about?
Staph Scalded Skin Syndrome.
Occurs as a reaction to epidermolytic toxin produced by the phage type 7I.
The area of desquamation can be away from the inital lesion as it is toxin mediated.
Assocaited with systemic upset, fever and irritability
Treated with oral flucloxacillin
What does POX virus cause?
Molluscum Contagiosum
Pink papules with an umbillicus with a central punctum. White material can be expressed from the centre.
Do not need treating, will resolve on their own, but can cryo off if patients unhappy with them.
A patient presents with small descrete areas of hypo and hyper pigment on their trunk. They came in today because they have been on holiday and noticed that they are not tanning uniformly, and there are ares of pale patches on their back. The rash is not palpable, but is occasionally itchy.
Diagnosis?
Pityriasis Veriscolour.
What is this? Does it need removing YES or NO?
Seborrhoeic keratosis
NO - it is benign.
Looks stuck on and warty, can be multiple, scattered and of varible sizes.
What is this? Does it need to be removed, YES or NO?
Pilar/ epidermoid cyst.
It is benign but patients may want it removed as it can become uncomfortable.
What is this? Does it need to be removed, YES or NO?
Dermatofibroma.
Dome shaped dermal nodule, with ill defined borders. It dimples when pinched.
Beign - does not need removing.
What is this? How can you treat it?
Capillary Haemangioma
Usually pale in first month of life and then rapidly enlarges. 100% disappear by 10 years but can be treated with B blockers if having local effects.
What is this?
How do you treat it?
Pyogenic granuloma.
It is a rapidly developing lesion, usually at the site of trauma. It is a solitary vascular nodule that bleeds very easily.
Needs to be curetted off.
What is this?
Does it need to be treated?
Actinic keratosis
Dry rough adherant scaly lesions on areas of chronic sun exposure. Keratinocyte atypia - pre malignant.
Needs to be treated, can excise or use diclofenac gel for 9 days!
What is Bowen’s disease?
SCC in situ - solitary well defined erythematous patch.
Needs to be removed as can result in invasive disease if left.
What is lentigo maligna?
A precursor to lentigo maligna melanoma.
It is atypical melaoncytes in situ, variations in hue, irregular macular stain.
Needs removing
What is this?
How do you treat it?
What are the complications?
Basal Cell Carcinoma.
Typically a pearly nodule with a rolled telangiectatic edge on the face. Can be nodular, morphoeic or pigmented.
Needs excision.
No potential for metasize.
What is this?
How is it treated?
What are the potential complications?
Squamous cell carcinoma
SCCs are persistently ulceerated or crusted, firm lesion, can be an indurated papule, plaque or nodule.
Needs to be excised - rare metasizes
What is this?
Keratoacanthoma
It s benign, but a DDx of SCC
Needs histological confirmation that it is not a SCC
Rapidly grwoing nodule, dome shaped with a keratinous crater.
What is this?
How is it treated?
What are the potential complications?
Melanoma.
There are different types: Superficial spreading, nodular, lentigo maligna, acral legtinous.
Prognosis is dependent on the tumour thicknesss, the thicker it is the more likely it is to have spread. <1mm is very good, >4mm only 50% 5 year survival.
Needs excising with wide margins and lymph node sampling. Lymphatic spead to local regional lymph nodes, haematoegnous spread to liver, lung, brain, and local spread to skin and sub cut tissue.
What is this?
What is it associated with?
Kaposis sarcom
It is a multisystem vascular neoplasia, results in violaceou lesions.
Due to HHV8.
Occurs in immunosupressed patients. HIV CD4 <200
A patient who has learning difficulites, siezures, and has this appearence?
Tuberous sclerosis.
Harmartomas (beign) form in the skin, brain, kidneys, eyes and heart.
What is this?
Xeroderma pigmentosa
Defective DNA repair so patients have photodamage from infancy.
Patient presents with altered bowel habit, bloating and non specific abdominal pain. She also has a itchy rash on her elbows and ankles. What is the diagnosis?
Coeliac disease.
The rash is Dermatitis Herpetiformis - gluten free diet should treat it, if not can use Dapsone.
A patient presents with heliotrope eye lids, periungial reddness with flat purpleish papules on their knuckles. They also C/O difficulty standing up from chairs and walking up stairs.
Dermatomyositis - can be a paranoplastic syndrome.
The knuckle lesions are called Gottron’s papules.
Can also present with ‘shawl sign’on back which is a photosensitive rash over the shoulders.
Need to investigate for malignancy, CXR, mamogram, CT and tumour markers.
What is this rash diagnostic of?
Lymes disease.
Erythema migrans
What is this? What disease is it associated with?
Necrobiosis Lipodica
Diabetes
What is this condition diagnostic of?
Sarcoidosis
Lupus Perni
What rash has a herald patch found in young adults?
Pityriasis rosea
May have viral cause, is self limiting.
