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What's causing the lesions on this woman's neck?

This patient had an itchy neck that was worrying her boss at the bakery where she worked. What was causing it? Dr Mike Wyndham describes the case


The patient

This 30-year-old woman was asked to come along by her employer at the bakery where she worked as she had been suffering from an itchy neck for the past week.

Her boss was concerned as she was involved with food handling. She was in good health apart from suffering from mild atopic eczema and asthma and denied suffering any major stress despite having two boisterous sons. She was the proud owner of a cat. On examination, there appeared to be multiple skin lesions, which were confined to her neck.

First instinct

Clearly, there were multiple lesions that appeared to be spread out but just localised to the back of the neck. The likelihood was that they were bites – but from what? Why was the condition so localised?

Differential diagnosis

• Bites

• Staphylococcal lesions

• Lichen simplex chronicus

There are several causes of bites. Fleas might have been a possibility in this case, as she was a cat owner, but one might have expected that the lesions would be more widespread and to affect the lower extremities. Mosquito bites might have been another cause as the lesions were grouped together, but there appeared to be a significant number and they were not very reactive – making this less likely.

Multiple lesions may be encountered with staphylococcal infection, particularly if they are being picked at, but are more likely to have caused a symptom of discomfort rather than itch.

Lichen simplex – alternatively called a neurodermatitis – is often grouped with eczema.

A patch found at the nape of the neck may be a few centimetres in size and can be intensely itchy. But this diagnosis could be ruled out with the absence of a patch and in a woman who denied any major stress.

The hidden clue

During the consultation, my eye was drawn to her eight-year-old son who had accompanied her to the surgery. He was scratching his scalp intensely. Was this just a coincidence?

Getting on the right track

I asked her if I could look at her son's hair. There they were – lots of nits. With a closer look at the roots of the patient's hair, the nits were obvious there too. A simple case of head lice.

I reminded myself of a rule of thumb I normally follow – if there is a localised ‘dermatitis', exclude a localised cause before looking for a generalised one.

Dr Mike Wyndham is a GP in Edgware, north London

What's causing these marks?

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