2  This previously well 4 year old child originally presented with fever and a cough. He was given Paracetamol, Ibuprofen and a cough mixture obtained from the chemist. Despite this he deteriorated and developed a progressive rash and skin lesions

a)  What is the character of the rash and skin lesions?

b)  Based on the history and the clinical photograph, list 3 differential diagnoses?

c)  How would you investigate  this condition?

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College Answer

a)  The rash is
•     Erythematous, 
•     Patchy 
•     Widespread 
•    Bullous formation or blistering

b)  Top 3 differentials
•    Stevens – Johnson syndrome (erythema multiforme major)
•    Drug eruption
•    Bullous pemphigoid

Less likely, but worthy of some marks
•    Staphyloccocal scalded skin syndrome
•    Toxic shock syndrome
•    Purpura fulminans

c) 
•    history in particular recent drug exposure, other symptoms of infective aetiology, Exposure to infected children
•    FBC, UEC, LFTs, CRP, COAGs
•    Serology – Mycoplasma and varicella
•    Skin biopsy
•    Blood cultures
•    MC&S of bullae

Discussion

This question closely resembles Question 15.1 from the second paper of 2012. Like all "name that rash" questions, this one suffers massively from the loss of the official college photograph.

So, in lieu of a sensible list of differentials, here is a list of random differentials for a severe generalised rash of uncertain aetiology:

Vascular causes:

  • Shower of emboli
  • Vascular insufficiency

Infectious causes:

  • Toxic epidermal necrolysis
  • Staphylococcal scalded skin syndrome
  • Viral exanthem/manifestations of viral infection
  • Fungal infection eg. candida

Neoplastic causes:

  • Cutaneous lymphoma/leukaemia

Drug-related causes

  • Stevens Johnson syndrome
  • Red Man syndrome (vancomycin)

Autimmune cause

  • Allergic reaction
  • Vasculitis
  • Erythema multiforme
  • Graft-versus-host disease

Traumatic causes

  • Burns

The standard work-up:

  • FBC for eosinophilia
  • Viral serology for HSV, VZV, HIV, EBC, CMV
  • Culture of exudate
  • Mycoplasma serology
  • Vasculitic screen
  • Skin biopsy