2a. Dermatological Diseases Flashcards
What is vitiligo?
An autoimmune disease with loss of melanocytes
What is malignant melanoma?
A tumour of the melanocyte cell line
What is telogen effluvium?
A common cause of temporary hair loss due to the excessive shedding of resting or telogen hair after some shock to the system
What is lipoatrophy?
Lipoatrophy is the diffuse loss of subcutaneous adipose tissue that most apparent in the face, buttocks, legs, and arms
What are milia?
A milium cyst is a small, white bump that typically appears on the nose and cheeks. Most common in newborns.
What is langerhans cell histiocytosis?
The overproduction of langerhans cellsnwhich build up to form granulomas.
Where are the symptoms of langerhans cell histiocytosis found?
skin and nails, mouth, bones, lymph nodes, pituitary gland, and thyroid gland.
What is merkel cell carcinoma?
Cancer of the merkel cells in the skin
What are the clinical features of merkel cell carcinoma?
Red nodule that grows quickly - often look like an infection or boil
What CD4+ T cell is associated with psoriasis?
TH1 and TH17
What CD4+ T cell is associated with atopic dermatitis?
TH2 and TH17
Which enzymes has reduced activity in porphria cutanea tarda?
Uroporphyrinogen synthase
What is the disease process of bullous pemphigoid?
Separating of the dermo-epidermal junction
What is epidermolysis bullosa?
An inherited skin disease causing the skin to blister and erode very easily.
What is an angioma?
This is an abnormal growth produced by the dilatation or new formation of blood vessels.
What is cutaneous photosensitivity?
An increased sensitivity to light. This may be normal or abnormal
What is a skin porphyria?
A group of disorders that result from a build up of natural chemicals that produce prophyrin in the body
What are the different types of porphyrias?
Phototoxic skin porphyrias
Blistering and fragility skin porphyrias
Acute attack porphyrias
Severe congenital porphyrias
What builds up in patients with erythropoietic protoporphyria?
Protoporphyria IX
What builds up in patients with porphyria cutena tarda?
Uroporphyrinogen III
What are some manifestations of S. Aureus infection?
Superficial lesions - boils to abscesses
Systemic life-threatening infections
Toxinoses - toxic shock and scalded skin syndrome
What is impetigo?
Highly infectious Group A Streptococcus infection. Mostly in children
What is cellulitis?
Deeper Group A Streptococcus infection into the dermis. Not associated with necrosis
What is necrotizing fasciitis?
Group A Streptococcus infection that rapidly destroys connective tissue
What is a toxinosis?
Any disease or lesion caused by the action of a toxin.
What is the diagnostic criteria for toxic shock syndrome?
Fever
Diffuse macular rash and desquamation
Hypotension
What toxins can be responsible for necrotising pneumonia?
Panto Valentine Leukocidin
Alpha-toxin
What is staphylococcus epidermis infection associated with?
Nosocomial infection - pathology is almost entirely restricted to the hospital setting
What are some skin diseases associated with group A streptococcus?
Impetigo
Cellulitis
Necrotising fasciitis
What is toxic epidermal necrolysis?
A rare, life-threatening skin reaction, usually caused by a medication. It results in keratinocyte death which causes epidermal detachment at the dermo-epidermal junction. The skin detaches in large necrotic sheets.
What are risk factors for a chronic wound?
Co-morbidities e.g. diabetes, arthritis
Poor circulation
Infection
Poor nutrition
What are the three types of epidermolysis bullosa?
Simplex
Junctional
Dystrophic
What is the condition associated with cafe au lait macules?
Neurofibromatosis
What type of hypersensitivity are associated with allergic reactions of the skin?
Type 1 and 4
What is the pathophysiology of a type 1 hypersensitivity?
- Proteins from the allergen are taken up and presented by antigen presenting cells.
- This activates T cells to Th2 Cells.
- These Th2 cells secrete cytokines which activated B cells.
- The B cells secrete IgE antibodies which bind to mast cells causing sensitisation.
- On subsequent exposure to the allergen, the mast cells degranulate and cause and allergic reaction.
What is a type 1 hypersensitivity?
This is an IgE mediated reaction that occurs up to 2 hours after exposure to thepathogen. It is a reproducible reaction and will occur after every exposure.
What is a type 4 hypersensitivity?
This is a delayed, antigen specific, T cell mediated hypersensitivity.
What is the pathophysiology of type 4 hypersensitivity?
- Allergen meets the skin and attaches to antigen presenting Langerhans Cells.
- These move through the lymphatic system where they bind with CD4+ Th1 cells and CD8+ T cells which are activated.
- They move back to the skin where they cause an effect.
What is a classical skin manifestation of type 4 hypersensitivity?
Dermatitis
What are some of the presentations of type 1 hypersensitivity?
Urticaria Angioedema Nausea Vomiting Sneezing Rhinorrhoea ANAPHYLAXIS
What is the progression of treatment of a type 1 hypersensitivity reaction?
- Antihistamies
- Anti-inflammatorys
- Adrenaline autoinjectors
What is tuberous sclerosis?
An autosomal dominant condition that causes growths to grow on various organs such as the brain, kidneys, lungs and eyes.
What is the cause of tuberous sclerosis?
the genes TSC1 and TSC2, which control the growth and division of cells by coding for tuberin and hamartin, are faulty.
What protein are patients with tuberous sclerosis unable to switch off?
mTOR
What are hamartomas?
Benign tumours that are made up of a variety of cell types form the tissue in which they arise
What is meant by the genetic heterogenecity of tuberous sclerosis?
The mutation can be in either the TSC1 gene or the TSC2 gene but the effect will still be the same
What is epidermolysis bullosa?
A group of genetic skin fragility conditions
What are the three types of epidermolysis bullosa?
Simplex - effects to the epidermis
Junctional - effects to the dermo-epidermal junction
Dystrophic - effects to the dermis
Which genes can be mutated in epidermolysis bullosa?
Keratin 5 Keratin 14 Laminins Integrins Collagen 17
Why do epidermolysis bullosa patients suffer from malnutrition?
So much of their energy goes into healing the skin that they as a result get malnutrition
What is a food allergy?
An adverse immune response to a food.
What are the most common food allergens?
Cow's Milk Chicken Eggs Fish Shellfish - especially prawns Soya Peanuts Tree Nuts Wheat
What are the three types of food intolerance?
Intolerance with unknown mechanisms e.g. to food additives
Pharmacologic intolerances - reactions to naturally occurring substances in food
Enzymatic intolerances e.g. lactose intolerance
What type of milk should be prescribed to babies with a cows milk allergy?
Extensively hydrolysed formula
What is extensively hydrolysed formula?
Contains cows milk proteins that have been broken into very shourt chains and therefore do not trigger an allergic reaction
What is the disease progression of lymphodema?
- Increased subcutaneous fat reduces lymphatic drainage due to swelling.
- Gradually worsening swelling causes chronic inflammation leading to fibrosis.
- Reduced tissue oxygenation and swelling results in bacterial overgrowth.
- Cellulitis develops easily and leads to further lymphatic damage.
- A downward spiral develops if left untreated and ultimately the skin becomes thick and warty and the lower leg and food become permanently enlarged, often grossly.
What is intertrigo?
Macerated red plaques that develop in the body folds.
What is acanthosis nigricans?
An abnormal velvety thickening and darkening of skin, especially in body creases. Often cause by other conditions e.g. obesity, stomach cancer
What are acrochordons?
Soft, small harmless skin coloured growths that hang off the skin - skin tags
What is pellagra?
A disease caused by deficiency of niacin (vitamin b3) and/or tryptophan
What are the 3 d’s of pellagra?
Dermatitis
Diarrhoea
Delirium/DEMENTIA
What are the different types of psoriasis?
Psoriasis vulgaris
Guttate
Palmoplantar pustular
Erythrodermic
What is Koebners phenomenon?
Psoriasis develops in an area of skin trauma
What is Auspitz sign?
Removal of surface psoratic scale reveals tiny bleeding portals
What are some comorbidities associated with psoriasis?
Psoriatic arthritis metabolic syndrome - obesity, hypertension, diabetes, lipid abnormalitites Crohns disease Cancer Depression Uveitis
What are the reversible side effects of topical steroids?
Pigmentary changes
Poor wound healing
Tachyphylaxis
Acnifrom eruptions
What are the irreversible side effects of topical steroids?
Atrophy
Striae - stretch lines
What are some of the causes of itch?
Pruritoceptive
Neuropathic
Neurogenic
Psychogenic
What is pruitoceptive itch?
Something in the skin that triggers itch
What is neuropathic itch?
Damage of any sort to the central or peripheral nerves causing itch
What is a neurogenic itch?
No evident damage in the CNS but itch caused by things like opiate effect on the CNS
What os psychogenic itch?
Psychological causes with no CNS damage
What is psychogenic itch?
Psychological causes with no CNS damage
What is psoriasis?
Psoriasis is an immune-mediated disease that causes raised, scaly patches on the skin due to systemic inflammation
What are the different types of psoriasis?
Chronic Plaque Psoriasis
Guttate Psoriasis
Palmoplantar Pustular Psoriasis
Erythrodermic and Widespread Psoriasis
What are the clinical signs of psoriasis?
Chronic Plaques
Psoriatic Nail Disease
What are some common sites involved in psoriasis?
Extensor surfaces - elbows and knees Scalp Sacrum Hands and Feet Trunk Nails
What is Koebners Phenomenon?
Psoriasis develops in an area of skin trauma
What is Auspitz sign?
Removal of the surface scale leaves tiny pin point bleeding patches
What are the treatments for psoriasis?
Topical therapies - vitamin D analogues, coal tar, steroids, emollients, dithranol
Phototherapy
Systemic treatments - immunosuppression (MTX), immunomodulation
What is the pathogenesis of acne?
- There is a blockage due to an increase in sebum production
- This leads to dermal inflammation and bacterial colonisation of the duct
- This causes occlusion of the pores
What are some of the causes of a flare up of acne?
Testosterone Running in families Periods Pregnancy PCOS Cosmetic Products Steroid Medication
What are some of the treatments for acne vulgaris?
- Avoidance of oily substances and triggers.
- Topical treatments – benzoyl peroxide, topical vitamin A derivatives, topical antibiotics
- Systemic treatments – Antibiotics, oral retinoid (Isotertinoin)
What is rosacea?
A skin condition which causes red patches and visible blood vessels on the face.
What are the different types of rosacea?
Erythematotelangiectatic
Papulopustular
Phymatous
Ocular
What are the treatments for rosacea?
Reduce aggrivating factors
Topical treatments - Metronidazole, Ivermectin (to reduce dermodex mite)
Oral therapies - tetracycline, isotretinoin
Vascular lasers - to treat telangiectasia
What is thought to cause rosacea?
There is an apparent role of the demodex mite.
What is lichen planus?
A chronic inflammatory condition that affects the skin, nails, hair, and mucous membranes, characterised by purplish, itchy, flat bumps.
What is the cause of lichen planus?
This is an immune-mediated disorder in which keratinocytes in the basal layer are attacked.
What is wickam’s striae?
Fine lace-like pattern on the surface of papules and buccal mucosa
What is bullous pemphigoid?
This is a chronic, inlfammatory, subepidermal, blistering disease.
What is the pathophysiology of bullous pemphigoid?
complement and inflammatory mediators.
- This attracts inflammatory cells.
- These release proteases which leads to blister formation.
What are the investigations of bullous pemphigoid and pemphigius vulgaris?
Biopsy
Direct Immunofluorescence
What is the treatment for bullous pemphigoid and pemphigus vulgaris?
Systemic steroids - corticosteroids
Immunosuppressive agents - Azathioprine, MTX
Tetracycline antibiotics
Topicals - emollients, topical steroids, topical antiseptics
Hygiene measures
What is pemphigus vulgaris?
This is a rare autoimmune disease that is characterised by painful blisters and erosions on the skin and mucous membranes.
What is the pathophysiology of pemphigus vulgaris?
- IgG autoantibodies bind to a protein called desmoglein 3, found in the desmosomes of keratinocytes.
- This causes the keratinocytes to separate from each other and be replaced by fluid.
What does Nikolsky sign positive mean?
Loose skin can slip away from the underlying layers
What is the difference between bullous pemphigoid and pemphigus vulgaris?
Bullous pemphigoid occurs when IgG attacks the cells of the basement membrane.
Pemphigus Vulgaris occurs when IgG attacks the proteins desmoglein 1 and 3 that are present in desmosomes of the keratinocytes.
What is hyperkeratosis?
Increased thickness of the keratin layer
What is parakeratosis?
Persistance of nuclei in the keratin layer
What is acanthosis?
Increased thickness of epidermis
What is spongiosis?
Odema between keratinocytes
What are the different classifications of dermatitis?
Contact allergic Contact irritant Atopic Drug-related Photo-induced or photosensitive Lichen simplex Stasis dermatitis
What is contact dermatitis?
This is a type IV hypersensitivity reaction that results from exposure to allergens or irritants.
What are some known irritants involved in contact dermatitis?
detergents, surfactants, extreme pH, water, organic solvents etc.
What gene plays a role in atopic dermatitis?
Filaggrin
What does crusting of eczema indicate?
Staph Aureus Infection
What is a characteristic lab finding in atopic eczema?
Elevated serum IgE
What are the treatments of dermatitis and atopic eczema?
Treatments include topical treatments such as emollients and topical corticosteroids. Systemic treatments such as immunosuppressants and systemic corticosteroids. There is also a need for allergen and irritant avoidance.
What is photosensitive dermatitis?
Eczematous reaction arising in response to electromagnetic radiation
What is stasis eczema?
This is a type of dermatitis that affects the legs and is associated with venous insufficiency.
What is the pathophysiology of stasis eczema?
There is fluid collecting in the tissues which leads to the activation of an innate immune response causing an inflammatory reaction.
What is seborrhoeic dermatitis?
Seborrhoeic dermatitis is a common, chronic or relapsing form of dermatitis that mainly affects the sebaceous, gland-rich regions of the scalp, face, and trunk.
What is thought to be the cause of seborrhoeic dermatitis?
It is associated with proliferation of various species of the skin commensal Malassezia, in its yeast form. Its metabolites may cause an inflammatory reaction.
What is discoid eczema?
Discoid eczema is a common type of eczema/dermatitis defined by scattered, well-defined, coin-shaped and coin-sized plaques of eczema.
What is the pathogenesis of atopic eczema?
Current theories identify cytokines, particularly IL-4 and IL-13 (Th2 pathway cytokines) and IL-22 cause barrier defects and inflammation that result in the clinical features of eczema.
What are the two main disease causing types of staphylococcus?
Coagulase positive - staph aureus
Coagulase negative - staph epidermis
What are some of the toxins that strains of staph aureus produce?
Staphylococcus Scalded Skin Syndrome Toxin
Panton Valentine Leukocydin
Enterotoxin
What drug is used to treat staph aureus infection?
Flucloxacillin (doxycycline if penicillin allergin)
What drugs are used to treat MRSA infection?
Skin and soft tissue options - doxycycline/co-trimoxazole/clindamycin)
Bactericidal option - Vancomycin
How do we diagnose a fungal infection?
Clinical appearance, wood’s light and skin scrapings
What should be used to treat a fungal infection?
Small areas of infected skin and nails can be treated with clotimazole cream or amorolfine (topical nail paint)
Scalp infections can be treated with terbinafine or itraconazole orally
What should be used to treat scabies?
Malathion lotion
Benzyl Benzoate
What drug is used to treat Group A strep infection?
Mild illness may not require antibiotic
Flucloxacillin
Necrotising fasciitis will require surgical debridement and antibiotics
What is pruritus?
Pruritus is the medical term for itch. This is an unpleasant, poorly localised, non-adapting sensation that provokes the desire to scratch.
What are the chemical mediators of itch?
Histamine, PGE2, Acetylcholine, Serotonin, Kallikrein, Interleukin 2, Substance P, Tryptase
What are some of the nerve transmission mediators of itch?
Unmyelinated C fibres
What are some of the central nervous system mediators of itch?
Opiates
What are the four causes of itch?
Neurogenic
Psychogenic
Neuropathic
Pruritoceptive
What is neurogenic pruritus?
Generated in the central nervous system in response to pruritogens but without any evidence of neural pathology.
What is psychogenic pruritus?
Itching caused by a psychological disorder.
What is neuropathic pruritus?
Results from neuronal pathology along the afferent pathway.
What is pruritoceptive pruritus?
Generated in the skin, usually by inflammation or other visible pathological processes involving the skin.
What are some categories of disease that are associated with pruritus?
kidney disease, thyroid disease, haematological diseases, paraneoplastic syndromes, liver and bile duct occlusions and psychogenic conditions.
What are some treatments for pruritus?
Sedative anti-histamines, emollients, antidepressants (doxepin), phototherapy and opiate antagonists (ondansetron)
What is the most common type of drug reaction?
Exanthematous Drug Eruptions
What is an Exanthematous Drug Eruption?
A non-predictable, T-cell mediated type 4 hypersensitivity reactions that are usually mild and self limiting.
Name some drugs associated with exanthematous drug eruptions…
Penicillins Sulphonamides Erythromycin Streptomycin Allopurinol Anti-epileptics NSAIDs Chloramphenicol
What will an exanthematous drug eruption present as?
A diffuse, symmetrical, maculopapular rash
What are the two causes of urticarial drug eruptions?
- This is usually an immediate IgE mediated type 1 hypersensitivity reaction that will occur upon rechallenge of a drug.
- It may also be caused by the direct release of inflammatory mediators from mast cells upon the first exposure to a drug.
What are two of the signs of an urticarial drug eruption?
Angioedema and anaphylaxis
What is a purpuric vasculititc drug reaction?
This is an indication of more serious drug reaction and occurs when there is drug-related bleeding into the skin.
What are pustular and bullous drug eruptions?
These reactions can range from mild to severe. Some examples of this include Steroid Acne, Acute Generalised Exanthematous Pustulosis, Vesicular and Bullous Reactions, Drug Induced Bullous Pemphigoid and Linear IgA Disease.
What is drug-induced hyperpigmentation?
Several drugs may slowly induce hyperpigmentation of the skin and mucosal surfaces, due to the deposition of melanin, haemosiderin, exogenous pigment or unknown mechanisms.
What is a fixed drug eruption?
Fixed drug eruption (FDE) refers to solitary or multiple oval plaques that arise over a few hours and may have central blisters.
Name some exampled of severe cutaneous adverse drug reactions?
Stevens-Johnson Syndrome
Toxic Epidermal Necrolysis
Drug Reaction with Eosinophilia and Systemic Symptoms
Acute Generalised Exanthematous Pustulosis
What is stevens-johnson syndrome and toxic epidermal necrolysis?
SJS/TEN is a rare, acute, serious, and potentially fatal skin reaction in which there are sheet-like skin and mucosal loss.
What is Drug Reaction with Eosinophilia and Systemic Symptoms?
This affects several organs at the same time, most commonly causing a combination of:
o High fever
o Morbilliform Eruption
o Haematological abnormalities
o Lymphadenopathy
o Inflammation of one or more internal organs
What is Acute Generalised Exanthematous Pustulosis?
This is an uncommon pustular drug eruption characterised by superficial pustules. It is also called toxic pustuloderma.
What is a drug induced photosensitivity?
This is a non-immunological skin reaction due to light activation of a photoreactive drug.
What diseases are associated with vitamin D deficiency?
Rickets
Osteomalacia
What are the three main cancers arising from epidermal cell lines?
Malignant melanomas - melanocytes
Basal cell carcinoma - basal cells
Squamous cell carcinoma - keratinocytes
What are the three types of melanocytic nevus (moles)?
Junctional
Compound
Intradermal
What are some of the positive effects of sunlight?
Role in vitamin D metabolism
Useful therapeutic agent
What are some of the negative effects of sunlight?
Major environmental toxin - Sunburn, Photoageing, Photocarcinogenesis
What are the diseases associated with vitamin D deficiency?
Rickets in Children – The softening and weakening of bones
Osteomalacia in Adults – This again is the marked softening of bones resulting in muscle weakness and bone fracture.
What are the two classifications of skin cancers?
Keratinocyte Skin Cancers and Melanocytes Skin Cancers.
What is malignant melanoma?
Melanoma is a type of skin cancer that arises from melanocytes along the basal layer of the epidermis.Malignant melanoma is difficult to treat and responds poorly to chemotherapy and radiotherapy.
What are mealnomas more likely to metastasise?
The melanocyte cells migrate to the skin from the neural crest during embryological development. This means that they are motile cells that can move around unlike keratinocytes. This mobility means that melanomas are much more likely to metastasise.
What factors influences the survivability of malignant melanoma?
Survival is dependent upon how deeply the melanoma penetrates the skin. This is known as the BRESLOW THICKNESS. The thinner the melanoma, the higher the likelihood of curing and the higher the survivability.
What is the ABCDE rule for malignant melanoma?
A - Asymmetry B - Border C - Colour D - Diameter E - Evolution
What is basal cell carcinoma?
Basal Cell Carcinoma is a type of skin cancer that arises from keratinocytes in the basal layer. These account for around 75% of skin cancers. They often present as a slow growing lump or a non-healing ulcer
What are the different types of basal cell carcinoma?
Nodular Superficial Morphoeic Pigmented Basosquamous
What are the features of a Nodular BCC?
A pearly white skin-coloured or pink bump with telangiectasic vessels.
What are the features of a Superficial BCC?
A flat, scaly, reddish patch that often looks like a small patch of dermatitis.
What are the features of a Morphoeic BCC?
A white, waxy, scar-like lesion without a clearly defined border. These are often more serious.
What are the features of a Pigmented
BCC?
A brown, black, or blue lesion with a slightly raised translucent border.
What is cutaneous squamous cell carcinoma?
Squamous Cell Carcinoma is a type of skin cancer that arises in the keratinocytes of the suprabasal layers of the skin. This accounts for around 25% of skin cancers.
What are the different forms of squamous cell carcinoma?
Cutaneous Horn
Keratocanthoma
Carcinoma Cunilatum
Majorlin Ulcer
What is a cutaneous horn?
A horn grows due to the excessive production of keratin.
What is a keratocanthoma?
A rapidly growing keratinising nodule that may resolve without treatment.
What is a Carcinoma Cunilatum?
A slow-growing, warty tumour on the sole of the foot.
What is a Majorlin Ulcer?
A cutaneous SCC that has developed in a scar or chronic ulcer.
What are the two precancerous lesions related to the skin?
Actinic Keratoses
Bowens Disease
What is Actinic Keratoses?
Dry, scaly patches of skin that have been damaged by the sun.
What is Bowen’s Disease?
This is described as carcinoma-in-situ where a solitary erythematous plaque is present.
What is xeroderma pigmentosum?
This is a rare skin disease where a person is highly sensitive to sunlight, has premature ageing and is prone to developing skin cancers
What is the cause of xeroderma pigmentosum?
There is an impaired Neucleotide Excision Repair System caused by one of seven gene abnormalities - XPA-G.
What are the tow genes that are associated with familial melanoma?
CDKN2A (tumour suppressor) and CDK4 (oncogene)
What is the function of the normal CDKN2A gene?
CDKN2A prevents cells from replicating when they contain damaged DNA by triggering cell cycle arrest at the G1/S checkpoint.
What is the normal function of the CDK4 gene?
CDK4 normally permits cell cycle progression by phosphorylation of retinoblastoma protein.
What does hyperkeratosis mean?
Increased thickness of the keratin layer
What does parakeratosis mean?
Persistence of nuclei in the keratin layer
What does acanthosis mean?
Increased thickness of epithelium.
What does papillomatosis mean?
Irregular epithelial thickening
What does spongiosis mean?
Oedema fluid between squamous cells that appears to increase the prominence of intercellular prickles.
What are the four classifications of inflammatory skin disease?
Spongiotic-intraepidermal oedema
Psoriasiform-elongation of the rete ridges
Lichenoid-basal layer damage
Vesiculobullous-blistering
What is Spongiotic-intraepidermal oedema?
Oedema in the epidermis e.g. Eczema
What is Psoriasiform-elongation of the rete ridges?
A lot of acanthosis of the epidermis e.g. Psoriasis
What is Lichenoid Basal Layer damage?
e.g. Lichen Planus and Lupus Erythematosus
What is Vesiculobullous-blistering?
e.g. Pemphigoid and dermatitis herpetiformis
What diseases are indications for cryotherapy?
Viral warts
Seborrhoeic Keratosis
Small actinic keratosis
Small skin tags
What is cellulitis?
This is a common bacterial infection of the lower dermis and subcutaneous tissue.
What is a leg ulcer?
A chronic leg ulcer is an open lesion between the knee and ankle joint that remains unhealed for at least four weeks.