Page 5 - DermPath Correlation

the dermal features of these conditions are not available to view. In these circumstances the
erroneous diagnosis of well differentiated SCC may be made.

Part 6:
Clinical Mnemonics See www.ddderm.blogspot.com to revise these differentials.

The conventional approach to teaching the pathological diagnosis of inflammatory skin
disease has been to assign the slide to a particular reaction pattern and look for the subtle
features that distinguish one disease from another that conventionally are known to cause
that reaction pattern. This works quite well but if you get the reaction pattern wrong you will
have trouble arriving at the correct diagnosis. You can combine the first obvious feature
with reaction patterns to minimise this risk. Convert the first obvious pathological feature
into a Clinical Feature ie Scales, Crusts, Pustules, Vesicles, Blisters and then use the
appropriate Clinical Mnemonic to give a list of Differential Diseases

Red Scaly Diseases

1. Diagnosing skin diseases is not difficult. You look at a rash and decide if it is red and scaly or
red and non scaly. If it is red and scaly you use the mnemonic PMs PET (PET is Psoriasis,
Eczema and Tinea. This is the Prime Minister'S Pet ( I used to always think of Kevin Rudd with a
Siamese cat called Petal sitting on his lap!) The first P of PM is for Pityriasis rosea or Pityriasis
versicolour, Pityriasis rubra pilaris, Pityriasis lichenoides and the M is for Mycosis fungoides, a T
cell lymphoma of the skin.) The S is for Solar damage and Scabies

Now we know that his pet cat is called PETAL. This helps us to remember Psoriasis, Eczema and
Tinea but also the less common red scaly diseases of A for Annular erythemas and L for Lupus
erythematosus ,Lichen Planus, Light eruption and Lues (an old name for syphilis)

2. If it is red but not scaly consider Cellulitis, Urticaria, Lupus, Light eruption, Drug reaction, Viral
exanthem or Annular erythema .The mnemonic is C U L at the Department
of Veterans Affairs EVIE(your girlfriend Evie) (CUL DVA EVIE) where EVIE stands for Erythema
multiforme, Vasculitis and Erythema nodosum and Infiltrates

3. If there are Pustules then the mnemonic is II

(aye aye) Infective( viral, bacterial, fungal) or Inflammatory eg psoriasis or a pustular drug reaction
or Sweet's syndrome. Common causes include Staph folliculitis , modified fungal infection or if the
vesicles are grouped herpes simplex. Pustules on the face are Acne, Rosacea, Staph folliculitis or