Mysterious brown marks have appeared under my armpits and breasts. I’m an otherwise healthy woman but I’m worried. DR SCURR reveals how to tell a common bacterial infection from something MUCH more sinister

Brown marks have appeared under my armpits and breasts, and I can’t seem to get rid of them. I tried off-the-shelf Canesten, which I was told could help – but it didn’t. I’m in my 30s, healthy and it’s really getting me down. I heard it could be a sign of prediabetes.

B Murray, Bicester.

Dr Martin Scurr replies: I am sorry to read of your distress, but I think there are good options for you. What you describe sounds like one of two possible conditions, erythrasma or acanthosis nigricans.

Erythrasma is the most likely: This is a common skin infection typically affecting the areas around the armpits, the groin and the folds under the breasts.

It’s triggered by the overgrowth of corynebacterium, a common skin bacteria, which thrives in warm sweaty skin, causing pinkish brown patches with defined edges – the patches may also be slightly scaly. It is a painless condition and not itchy.

It’s treated with an antibiotic cream (such as fusidic acid or clindamycin) which needs to be prescribed by your GP – and not an antifungal such as Canesten (a fungal infection is recognisable – scaly, but with defined red inflamed edge; e.g. ringworm).

Brown marks have appeared under my armpits and breasts, and I can’t seem to get rid of them. I tried off-the-shelf Canesten, which I was told could help – but it didn’t (Stock image)

Some GPs will use a diagnostic tool called a Wood’s light to confirm erythrasma – it emits UV light and will cause the skin to fluoresce in the presence of the bacteria that cause erythrasma.

Acanthosis nigricans is also a possibility. As you say, this is associated with diabetes – it causes symmetrical brown patches in the sites you mention. Importantly, it looks and feels different as it has a velvety texture and looks more like large rough smudges.

In short, when someone is prediabetic, their cells become resistant to insulin, meaning the body needs to produce more of this hormone to keep blood sugar under control.

But insulin is also a growth-promoting hormone, so high levels can stimulate growth signals elsewhere, including in skin cells – this in turn causes them to multiply and become thicker.

And because friction can accentuate these changes, these patches are noticeable around skin folds such as the armpits.

If this is the suspected cause then your GP will conduct a blood test for diabetes. The patches can fade when the underlying insulin resistance is treated and brought under control, usually by weight loss.

I am 80 and had a metal plate inserted in my left femur [thigh bone] following a fall 18 months ago. I was told I was not suitable for hip replacement because of other health issues. However, my hip joint is in very poor condition and I am in lots of pain. I’d like to take painkillers – but which is best for someone on warfarin (for atrial fibrillation)?

Bryn Owen, Sheffield.

Dr Scurr replies: It sounds as though you are dealing with chronic pain from osteoarthritis due to wear and tear in your left hip.

It is not entirely clear why you didn’t have a hip replacement when your fractured thigh was operated on – it could be that as well as your other health issues, the location of the fracture played a role: Usually the hip is replaced when the femur fracture involves the hip joint itself.

An injection of corticosteroid might help ease pain and inflammation – but this is not an option for you because of your metal plate (there can be an infection risk as you’re introducing an immunosuppressant – the steroid – and opening up a route for germs via a needle).

I am 80 and had a metal plate inserted in my left femur [thigh bone] following a fall 18 months ago. However, my hip joint is in very poor condition and I am in lots of pain (Stock image)

In terms of pain relief, the fact you take the blood thinner warfarin rules out non-steroidal anti-inflammatory drugs, such as ibuprofen, as these increase the risk of internal bleeding.

Paracetamol might give you relief. Codeine is a better option pain-wise but is potentially addictive and commonly causes constipation. You could combine the two with co-codamol tablets, available from a pharmacy – but this should only be as a stopgap, for a month or two at the most, while waiting for hip surgery.

In the meantime, you might also benefit from seeing an experienced physiotherapist to help improve your gait, which could be worsening the pain.

Unless there is any other factor affecting your suitability for surgery, on the basis this is your best option, my advice is that you ask to be reassessed for this.

IN MY VIEW…

It’s looking up for school dinners

I went to a Jesuit school and, as a doctor, I’m often reminded of that old Jesuit maxim: ‘Give me a child until he is seven and I will show you the man.’

This refers to good education becoming ingrained, but I think it is also true for health – teaching children about food combines both, showing them how to lead a long and healthy life.

The increase in childhood obesity shows that we have lost the way, despite initiatives aimed at improving school dinners – Jamie Oliver’s and Prue Leith’s among those that fell by the wayside.

Now the Government has announced a new plan – no deep-fried food, sweetened desserts allowed just once a week in primary schools and so on.

There have been the usual complaints about ‘the nanny state’ but it should not be responsible for feeding children rubbish, as it does currently.

And with the Food Standards Agency in charge, I am hopeful that this time things will change.

• Write to Dr Scurr at Good Health, Daily Mail, 9 Derry Street, London, W8 5HY or email drmartin@dailymail.co.uk. Replies should be taken in a general context. Always consult your own GP with any health concerns.