MRCP revision battle 50.1: Gangrene and Necrotising Fasciitis

A day dedicated to dermatology...


MRCP revision battle 50.1: Gangrene and necrotising fasciitis
MRCP revision battle 50.2: Acne Rosacea
MRCP revision battle 50.3: Seborrhoeic dermatitis
MRCP revision battle 50.4: Alopecia
MRCP revision battle 50.5: Discoid lupus erythematosus
MRCP revision battle 50.6: Bullous Pemphigoid and Pemphigus Vulgaris
MRCP revision battle 50.7: Erythrasma




MRCP revision battle 50.1: Gangrene and necrotising fasciitis


A couple of grim topics: gangrene and necrotising fasciitis.


Gangrene

Gangrene is death of tissue due to ischaemia.  It can be subdivided into:

• dry gangrene = ischaemia only
• wet gangrene = ischaemia plus infection

Management is surgical with debridement and IV antibiotics



Necrotising fasciitis 




Necrotising fasciitis is a rapidly spreading infection of the deep fascia.


Type 1 is caused by mixed anaerobes and aerobes, classically occuring in diabetes and post surgery
Type 2 is usually caused by streptococcus pyrogenes, which is a group A beta haemolytic strep.



Fournier's gangrene is a subtype of necrotising fasciitis which affects male genitalia/the perineal area.
Meleney's gangrene is a subtype of necrotising fasciitis which occurs after an operation


Treatment of necrotising fasciitis is with debridement.



Mortality is around 70%.



Onwards to acne rosacea...

MRCP revision battle 50.2: Acne Rosacea

Acne rosacea is a skin condition that affects the face.

The first sign is often facial flushing.


Other features of acne rosacea include:

• erythema of face
• papules/pustules
• telangiectasia
• eye involvement - eg dry eyes
• rarely rhinophyma 

The cause is not known although  demodex follicularum is hypothesised to be involved as it occurs in larger numbers on suffers of acne rosacea than the general population.  Overuse of topical steroids can cause a condition like acne rosacea.


If the condition is mild topical metronidazole is used.
In severer cases oral oxytetracycline is given.




On to some flakey skin....

MRCP revision battle 50.3: Seborrhoeic dermatitis

Seborrhoeic dermatitis, AKA seborrhoeic eczema, is a skin condition characterised by dandruff and sometimes dry, erythematous flakey skin.


It is associated with a fungus called Malassezia furfur (previously known as Pityrosporum ovale).  However, it is not contagious.


Treatment is with ketoconazole 2% shampoo and anti-fungal cream.


Severe forms of seborrhoeic dermatitis are associated with Parkinson's disease and HIV.

Complications include otitis externa and blepharitis.


Now for some hair loss...

MRCP revision battle 50.4: Alopecia

This is a topic close to many men's hearts - alopecia (=hair loss).

We will consider alopecia in 3 sections:

1. autoimmune
2. scarring
3. non-scarring

Alopecia areata

• Alopecia areata is thought to be an autoimmune condition in which there are 'patches' of hair loss.
• hair regrows in 50% of sufferers within a year
• hair regrows in 80-90% of sufferers eventually
• it is associated with:
• autoimmune thyroid disease
• pernicious anaemia
• addisons
• vitiligo
• nail dystrophy
• cataracts
• alopecia totalis refers to complete loss of all hair on scalp
• alopecia universalis refers to loss of all body hair

Scarring alopecia

Causes of scarring alopecia include:

• infections: TB, syphyllis
• radiotherapy
• sarcoidosis
• lichen planus

Non-scarring alopecia

Causes of non-scarring alopecia include:

• areata
• hypopituitarism
• hypo/hyper thyroidism
• pregnancy
• OCP
• carbimazole
• thiouracil
• lithium
• iron deficiency
• chronic illness

 Next up... some discoid lupus...

MRCP revision battle 50.5: Discoid lupus erythematosus

Discoid lupus erythematosus is a skin condition characterised by:

• erythematous plaques with 
• slight scaling with the 
• inside hypopigmented compared to the edge.  As they age they develop
• keratin plugs in the centre.

Young females tend to be most commonly affected.

The lesions are photosensitive and tend to occur on the face, neck and scalp.

It is associated with SLE but less than 5% of cases progress to SLE.


First line treatment is topical steroids.
Second line treatment is hydroxychloroquine.



Now to a pair of blistering diseases that have always confused me...

MRCP revision battle 50.6: Bullous Pemphigoid and Pemphigus Vulgaris

Personally I have always mixed up bullous pemphigoid and pemphigus vulgaris so I'm hoping by tackling them in the same battle the differences will become apparent...





Note that pemphigus vulgaris can be drug-induced, with culprits including penicillamine, captopril and cephalosporin.

Pemphigus vulgaris is more common in Ashkenazi Jews.


On to something that glows coral red under woods lamp...

MRCP revision battle 50.7: Erythrasma

Erythrasma is a skin condition characterised by asymptomatic initially pink patches that become brown as the skin sheds.


Erythrasma is caused by corynebacterium, a gram positive bacteria.


If a woods lamp is held near a patch of erythrasma the erythrasma glows coral red due to porphyrins released by the bacteria.


It is commonest amongst diabetics and the obese.


Treatment is with topical fusidic acid/clindamycin or oral erythromycin if extensive.