UKMLA: Dermatology

Acne: Which bacteria can cause it?

Propionibacterium acne’s

Acne: What is the classification?

• Non-inflammatory→ blackheads and whiteheads

• Inflammatory→ papules, pustules and nodules

• Severe→ nodules (cysts), scars, acne fulminans and acne conglobata

Acne Fulminans: What is the presentation?

Painful cysts, fever, fatigue→ review urgently in 24 hours

Teenager males mostly affected

Acne Conglobata: What is the presentation?

Uncommon presentation of severe nodular/cystic acne with interconnecting sinus tracts and extensive scaring

Acne: What is the management of mild-moderate acne?

2 of the following topical treatments:

• Benzoyl peroxide

• Clindamycin

• Tretinoin/adapalene

Acne: What is the management of moderate-severe acne?

12 week course of:

• Topical tretinoin/adapelene + benzoyl peroxide

• Topical azelaic acid with oral lympecycline or doxycycline (tetracycline antibiotics)

• Give trimpethoprim and erythromycin in pregnant women

Acne: What is the management of severe acne?

Isotretinoin but:

• Screen for mental health disorders before as it can worsen it

• Start females of contraception as it is teratogenic

• Make sure the patient is aware it can cause blistering and skin peeling

Actinic Keratosis: What is it?

Pre-malignant skin condition that leads to squamous cell carcinoma

Actinic Keratosis: What is the cause?

Actinic keratoses are thought to arise due to sun exposure leading to DNA damage within the keratinocytes

Actinic Keratosis: What is the typical presentation?

Thick papule or plaques with rough, surface

Occurs on sun-exposure area of skin

Actinic keratosis: What are the risk factors?

• Type I or II skin (fair, burns easily)

• History of sunburn or extensive sun exposure

• Outdoor occupation or hobbies

• Immunosuppression

Actinic Keratosis: What is the management?

• 5-Fluorouracil (a cytotoxic agent)

• Non-steroidal anti-inflammatory drugs (NSAIDs)

• Imiquimod (an immune response modifier)

Patient education on sun-protective measures is also an essential part of management

Alopecia: What is trichotillomania?

Hair-pulling disorder

Alopecia: What is alopecia arteta?

Autoimmune cause of patchy hair loss

Alopecia: What is androgenetic alopecia?

Diffuse thinning of the scalp hair

Alopecia: What is telogen effluvium?

Temporary hair loss due to excessive shedding of resting hair (e.g. after child-birth or weight loss)

Alopecia: What is the management?

• Wig

• Topical steroids → clobetasol propionate

• Minoxidil

• Dithranol (skin stain)

BCC: What is the pathophysiolgy?

• Originates from basal keratinocytes

• DNA damage due to UV radiation

• Most common skin cancer

BCC: What is the classification?

• Nodular→ most common, shiny pink nodule

• Sclerosing→ firm, scar-like plaque

• Superficial→ scaly red patches (mistaken for eczema or psoriasis)

BCC: What are the symptoms?

• Very slow growing

• Local destruction can occur

• Usually painless and ulcerates

• Flesh coloured nodules with central depression, pearly surface, rolled edge, and telangiectasia

• They can can necrose and ulcerate in the centre ('rodent ulcer)

BCC: What are the investigations?

• Excision biopsy with 4mm margin

• If lesion is 2cm diameter or on ear/lip/face/genitals/hand/feet etc or patient is immunocompromised or had BCC before→ excision biopsy with 6mm margin

BCC: What is the treatment?

• Almost always treated surgically with excision using a 4mm margin (6mm for high-risk lesions)

• Micrographic surgery for poorly-defined areas

• Radiotherapy

• Other options: curettage and cautery, topical 5-fluorouracil, topical imiquimod, cryotherapy for low-risk lesions

Cellulitis: What is the pathophysiology?

The most common offending organisms are Streptococcus pyogenes or Group A beta-haemolytic streptococci

Cellulitis: What are the risk factors?

• Breaks in the skin

• Chronic lymphadenopathy

• Obesity

• Diabetes

• Immunosuppression

• IV drug use

• Previous history of cellulitis

Cellulitis: What are the symptoms?

Generally caused by Streptococcus and/or Staphylococcus organisms.

• Erythema

• Calor (heat)

• Swelling

• Pain

• Poorly demarcated margins

• Systemic upset: fever, malaise

• Lymphadenopathy

• Rarely blisters and pustules (severe disease)

• Often evidence of breach of skin barrier e.g. trauma, ulcer etc.

Cellulitis: What is the Eron classification?

• Class 1→ no systemic toxicity or uncontrolled comorbidities

• Class 2→ systemically unwell

• Class 3→ acute confusion, tachycardia, tachypnoea, hypotension, or unstable comorbidities

• Class 4→ sepsis or necrotising fasciitis

Cellulitis: What are the investigations?

• Blood tests - FBC (high WCC), CRP, U+E (may be AKI if severe infection), blood cultures

• Wound swab if there is an open wound

• US to check for abscess

Cellulitis: What is the management?

• Class 1→ flucloxacillin

• Class 2→ admit

• Class 3 + 4→ admit for IV antibiotics

• Patients with infection near eyes or nose→ co-amoxiclav (or metronidazole and clarithromycin if allergic)

Chicken Pox: What is the virus name?

Varicella-zoster virus HHV3

Chicken Pox: What is the infectious period?

1-2 days before rash appears and until 5 days until after rash appears.

Onset to symptoms is 14 to 16 days from exposure

Chicken Pox: What are the symptoms?

• Raised,red itchy spots

• Fluid-filled vesicles

• Within 5 days, it crusts over

Chicken Pox: What is the management?

• Prevent itching

• Oatmeal baths

• Chlorpenamine to relieve itching

• Paracetamol

• If pregnant or neonate-. IV aciclovir

• PEP for immunocompromised patient is oral aciclovir 7-14 days after exposure

Contact Dermatitis: What are the two types?

• Irritant→ exposure to chemicals or solvents

• Allergic→ delayed type 4 hypersensitivity reaction

Contact Dermatitis: Which immune cells are involved?

T cells mediate the delayed type 4 hypersensitivity reaction.

Contact Dermatitis: What are the symptoms of irritant contact dermatitis?

• Burning

• Pain

• Stinging

Contact Dermatitis: What are the symptoms of allergic contact dermatitis?

• Itchy

• Eczematous rash

• Occurs 24-48 hours after exposure

Contact Dermatitis: What is the investigation?

Patch testing

Contact Dermatitis: What is the management?

• Emolient use

• Topic steroids

• Anti-histamines

Folliculitis: What is the cause?

Staph aureus

Folliculitis: What is the name of the type of folliculitis common in immunocompromised patients?

Eosoniophilic folliculitis→ requires biopsy for investigation!!

Folliculitis: What are the signs and symptoms?

• Papules

• Pustules

• Never on hands or soles of feet

Folliculitis: What is the management?

Topical antibiotics and chlorhexidine scrub

Hemangiomas: What are they?

A common benign vascular tumour that occurs in infancy

Hemangiomas: What is the typical clinical presentation?

• Occurs in infancy or pregnancy

• Typically affects head/neck

• Common in females

• Grows over time

Hemangiomas: What is the management?

• Leave the lesion and do nothing

• Propranolol if it needs intervention e.g. near the eye

Hemangiomas: What is the conservative management?

Leave the lesion and do nothing

Impetigo: What is it?

• Contagious infection of the epidermis

• Occurs in infants and school-age children (typically 0-4 years old)

Impetigo: What is the pathophysiology?

• Caused by staphylococcus aureus (80%), group A haemolytic streptococcus (10%)

• The bacteria produces exotoxins that target desmoglein-1

Impetigo: What are the risk factors?

• Pre-existing skin conditions

• Immunosuppression

• Direct contact with infected individual

• Crowding, humidity and poor hygiene

Impetigo: What is the classification?

• Bullous→ fluid filled lesions greater than 1cm

• Non-bullous→ no fluid filled lesions

Impetigo: What are the symptoms?

• Erythematous macule

• Superficial erosion with golden crust

• Sores (non-bullous)

• Blisters (bullous)

Impetigo: What is the management?

• Local non-bullous→ hydrogen peroxide 1% cream for 5 days

• Widespread non-bullous→ oral flucloxacillin for 5 days or fusidic acid cream for 5 days

• Bullous→ antibiotics for up to 7 days

• Children should be off school until all lesions are healed or until 48 hours after starting treatment.

Measles: What is the cause?

Measles morbillivirus (paramyxovirus)→ transmitted via droplets (nose, throat or mouth)

Measles: What is the epidemiology?

• Affects anyone at any age

• Caused by measles morbillivirus→ single stranded, RNA virus

• 7-21 days incubation period

• Infectious from 4 days before rash appears until 4 days after the rash appears

Measles: What are the symptoms?

• Prodromal symptoms (pyrexia and cough)

• Fever over 40 degrees

• Coryzal symptoms

• Conjunctivitis

• Koplik spots→ small grey discolourations in the mouth

• Rash appears behind ears then spreads to trunk and limbs over 3-4 days

  

Measles: What is the investigation?

• Oral fluid sample for:

• Measles RNA 1-3 days after rash onset

• Measles-specific IgM/IgG → 3-14 days after rash

Measles: What is the management?

• Analgesia

• Fluids

• Vitamin A

• Stay off school for at least 4 days after rash appears

• Stay away from pregnant women and immunocompromised people

Measles: How can it be prevented?

MMR vaccine

Necrotising Fasciitis: What is the classification?

• Type 1→ polymicrobial (most common)

• Type 2→ monomicrobial (e.g. strep or staph)

• Type 3→ rare but associated with contaminated seafood or seawater exposure

• Type 4→ rare but fungal associated with burns or trauma

Necrotising Fasciitis: What is gas gangrene?

Caused by clostridium perfingens → characterised by crepitus on auscultation

Necrotising Fasciitis: What is fournier’s gangrene?

Necrotising fasciitis of the perineum

Necrotising Fasciitis: What are the bedside investigations?

Bedside:

• Wound swab to identify pathogens

• Blood gas may show metabolic acidosis; hyperglycaemia and raised lactate common

Necrotising Fasciitis: What is the management?

• Broad-spectrum IV antibiotics within the first hour; commonly used include tazocin, meropenem, clindamycin, and linezolid.

• Surgical debridement

Necrotising Fasciitis: What are the differentials?

• Cellulitis: Localised erythema and swelling, but lacks rapid progression and severe systemic illness.

• Deep vein thrombosis: Localised pain and swelling, limited skin changes, and patients are not systemically unwell.

• Osteomyelitis: Fever, pain, and swelling but usually more chronic and does not progress rapidly.

Psoriasis: What is the diagnostic feature?

Psoriasis is a chronic autoimmune disease characterised by well-demarcated, erythematous, scaly plaques.

Psoriasis: What are the 5 different types?

• Chronic plaque psoriasis (most common, knees, elbow, scalp, lower back)

• Flexural psoriasis→ smooth without scales in flexures and skin folds

• Guttate psoriasis→ small, tear-drop shaped after strep infection in young adults

Psoriasis: What are the risk factors?

• Skin trauma

• Streptococcus, HIV infections

• B-blocker, anti-malarials, lithium, NSAIDS

• Steroid withdrawal

• Stress

• Alcohol + smoking

• Cold/dry weather

Psoriasis: What are the signs?

• Nailbed pitting → superficial depressions in the nailbed

• Oncyholysis → separation of nail plate from nailbed

• Subungual hyperkeratosis→ thickening of the nailbed

Psoriasis: What is the management?

1. Corticosteroid + vitamin D

2. Vitamin D only 2x daily

3. Corticosteroid only 2x daily

4. Phototherapy UVA

5. If the above doesn’t help then give either methotrexate, cyclosporin (urgent help, pregnant or female of childbearing age) or acitretin

Scabies: What is the cause?

Sarcoptes scabei mite → causes type 4 hypersensitivity reaction 30 days after initial infection

Scabies: What are the symptoms?

• Intensely itchy rash

• Worse at night

• Affects flexures of wrist, axilla, abdomen and groin

• Superficial burrows can be seen

Scabies: What is norwegian/crusted scabies?

Scabies in immunocompromised patients e.g. HIV

Scabies: What is the management?

1. Topical permethrin 5% for 12 hours, repeat in 7 days ( Apply to cool and dry skin, to the whole body → allow lotion to dry before dressing and leave it on for 12 hours before washing off→ repeat after 7 days)

2. Crotamiton cream to relieve itching

3. Treat everyone from the same household, on the same day

Scabies: What is the management of Norwegian scabies?

Oral ivermectin + treat household members

Can use in combination with permethrin for maximum effect

Shingles: What is the cause?

Reactivation of varicella zoster virus in the nerve ganglia after chickenpox

Shingles: What is the epidemiology?

• Affects the elderly

• If a young adult is affected, investigate for an underlying immune condition

Shingles: What are the symptoms?

• Tingling feeling

• Erythematous papules within a few days→ fluid filled vesicles→ bursts and crusts

• Painful rash

Shingles: What is the management?

• Valaciclovir 1g 3x a day for 7 days

• IV antivirals in hospital if immunocompromised

• Avoid contact with vulnerable people e.g. pregnant women

• Manage pain via NSAID or amitriptyline if still in pain

Shingles: How can it be prevented?

Shingles vaccine→ offered to people in their 70’s as a one-off vaccine

SCC: What is the pathophysiology?

• Originates in epidermal keratinocytes

• Pain, tenderness or bleeding

• Grows over few weeks or months

SCC: What is the presentation?

• Keratinised

• Scaly horn or plug (bump)

SCC: Which lesions can develop into SCC?

• Actinic keratosis

• Marjolin ulcer→ due to previous injury e.g. burns or scars

• Bowen’s disease→ precancerous lesion which is defined by irregular, red, keratinised scaly plaques

SCC: What is the treatment?

• Almost always treated surgically with excision using a 4mm margin (6mm for high-risk lesions)

• Micrographic surgery for poorly-defined areas

• Radiotherapy

• Other options: curettage and cautery, topical 5-fluorouracil, topical imiquimod, cryotherapy for low-risk lesions

Topical Steroids: Which is the least potent?

Hydrocortisone

Topical Steroids: Which is mildly potent?

Alclometasone

Topical Steroids: Which is moderately potent?

Mometasone

Topical Steroids: Which is very potent?

Betametasone and Fluticasone

Topical Steroids: Which is the most potent?

Clobetasol→ “dermovate”