# A spreading rash and mouth sores in a 28-year-old: a case to work up

> A dermatology emergency case for medical students: a 28-year-old with fever, a painful spreading rash, red eyes and raw mouth sores. What to ask, red flags, examination, first tests and the differential.

- Dermatology · Intermediate · about 20 minutes
- Web page: https://www.medikarya.in/case-studies/28-year-old-man-with-a-spreading-rash-and-mouth-sores
- Work up this patient: https://www.medikarya.in/case-studies/28-year-old-man-with-a-spreading-rash-and-mouth-sores

## How the patient presents

A previously healthy young man comes to emergency with a high fever, a painful rash on his face and body, red eyes, and raw sores on his lips and inside his mouth that have got worse fast. He was treated for a sore throat a few days ago.

## Why fever with a rash and mouth sores matters

A painful rash with sores in the mouth and red eyes can be a viral illness, an infection, or a severe reaction that behaves like a burn. Find out which quickly: assess how much skin and how many surfaces are involved, and protect the eyes, fluids and nutrition.

## What to ask in the history

- When the rash started and how fast it has spread; is the skin painful
- Every medicine in recent weeks, including antibiotics, painkillers and anything bought without a prescription
- Fever, sore throat, cough
- Eyes, genitals, passing urine
- Blisters or peeling
- Previous reactions to medicines
- Cold sores, HIV

## Red flags

- Blistering or peeling skin
- Sores on more than one surface (mouth, eyes, genitals)
- Eye pain or redness
- Low blood pressure
- Breathing difficulty
- Unable to eat or drink

## What to examine

- Observations
- Skin: the type of lesion, how much of the body is involved, pain
- Whether the skin slides off with gentle pressure
- Mouth, eyes, genitals
- Lymph nodes, chest

## First investigations

- Full blood count, kidney and liver function, electrolytes, glucose
- Blood cultures
- Skin biopsy
- HIV test, mycoplasma test
- An urgent eye review
- A recognised severity score

## Differential diagnosis of fever with a rash and mouth sores

Grouped, not ranked. Which one fits this patient is for you to work out in the case.

### Infections

- Herpes simplex
- Mycoplasma
- Staphylococcal scalded skin
- Viral rashes such as measles or chickenpox

### Reactions to medicines

- Stevens-Johnson syndrome or toxic epidermal necrolysis
- DRESS
- Erythema multiforme major

### Other

- Pemphigus
- Pemphigoid

## Common mistakes

- Continuing a medicine that could be the cause.
- Underestimating the fluid lost through damaged skin.
- Missing eye involvement.

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A study guide for medical students, not medical advice. Follow your institution's protocols in practice.