The patient
A 46-year-old woman presented with a rash that had recently developed on her face. It had first appeared a few months previously and had remained since, at times more pronounced than others.
She had no history of dermatological problems and the rash was non-itchy – she was mainly concerned about the cosmetic appearance. There was little of note in her past records and she was on no regular prescribed or over-the-counter medication.
Nor had she tried much in the way of self-treatment for her rash, other than the occasional application of some moisturiser.
First instinct
The examination of such rashes rarely adds much useful information over and above your first impression – which in this case was of a symmetrical erythematous eruption affecting both cheeks. Closer scrutiny revealed the rash to be slightly raised – but there were no other clues apparent, and my patient appeared otherwise well. Most facial rashes in this age group turn out to be rosacea or seborrheic eczema, though other possibilities include perioral dermatitis, allergy and photosensitive rashes, plus a few more obscure possibilities.
Differential diagnosis
• Rosacea
• Seborrheic eczema
• Perioral dermatitis
• Allergic rash
• Photosensitivity
• SLE
Rosacea is very common and this patient was in the typical age group. But she did not admit to any flushing and there were no telangiectasia visible on close examination.
Seborrheic eczema, though another common presentation, also didn't quite seem to fit the bill. There was no scaling evident and there was no involvement of the nasolabial folds or scalp. Nor could my patient be persuaded that her rash was itchy.
Perioral dermatitis can produce a similar appearance, but the distribution – as the name would suggest – is usually restricted to the area around the mouth rather than the cheeks.
Primary irritant or allergic contact eczema might have been a distinct possibility had it not been for the fact that my patient insisted the rash seemed unconnected to the use of any creams or cosmetics – which she only applied very rarely anyway.
But she agreed that her symptoms seemed worse after exposure to sunlight, which pushed photosensitivity much higher up the list of possibilities.
I usually associate this phenomenon with medication, but we weren't prescribing her any and nor was she taking any over-the-counter drugs. Plants are known to photosensitise – so called ‘phytophotodermatitis' – but the distribution was atypical and she was not a keen gardener.
SLE remained a possibility, but was unlikely just by virtue of its relative rarity.
The hidden clue
I knew that connective tissue diseases have many systemic manifestations and I dimly recalled that any associated facial rash might be photosensitive. This prompted me to expand on the history – at which point she confirmed that, yes, she had been feeling out of sorts lately and had been suffering unexplained joint aches and pains.
Getting on the right track.
A rash is often viewed as a welcome ‘quickie' in the average surgery. This can lead to us overlooking the fact that rashes can be a sign of significant systemic disease – and that a perfunctory history might overlook key clues. More detailed inquiry revealed some weight loss and a dry mouth. Subsequent investigation showed an elevated ESR and positive auto-antibodies – and the diagnosis of SLE was confirmed by the rheumatologist a few weeks later.
Dr Keith Hopcroft is a GP in Laindon, Essex
Facial rash
