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In order to diagnose Sweet’s syndrome (SS), your doctor or dermatologist will need to take a skin biopsy for detailed microscopic examination to confirm diagnosis and rule out any other conditions that might be confused with SS.
Read more about how SS is diagnosed here.
What is a biopsy?
A biopsy is a medical procedure that involves taking a small sample of tissue so that it can be examined under a microscope. In patients with suspected SS, the sample will be taken from a skin lesion – an area of skin where abnormal changes have occurred.
Is a biopsy always necessary?
Yes, SS cannot be accurately diagnosed via visual examination of skin lesions or blood tests alone. A biopsy is needed to detect certain changes in the tissues.
Are there different types of biopsy?
Yes, and the 2 main types of biopsy used in patients with possible SS are:
- A punch biopsy – the commonest type of biopsy. A special instrument is used to punch a small hole in the skin to obtain a skin sample.
- An incisional biopsy – where a larger section of tissue is taken away with a scalpel. This is often needed to accurately diagnose an unusual form of SS called subcutaneous Sweet’s syndrome or Sweet’s panniculitis.
How many biopsies will I need?
The number of biopsies needed can vary from patient to patient. Some will only need one or two, while others will need more.
Why is this?
SS can sometimes be difficult to diagnose, and biopsy results may vary. Therefore, more than one biopsy may be needed so that your doctor can compare results and get a better idea of what’s going on.
SS can occur at the same time as other conditions that affect the skin. For example, on rare occasions SS can develop alongside the skin condition erythema nodosum. This means that you may need biopsies from different lesions, some of which may be on different parts of the body. This can then help to determine which conditions you may or may not have.
Sometimes, the changes that can potentially occur in lesions that are more than seven-days-old or older can affect biopsy results. This means that in order to get an accurate diagnosis you might need to have another biopsy of a newer lesion.
Does a biopsy hurt?
Before you have a biopsy you will be given a local anaesthetic to numb the area. After the anaesthetic has worn off you may experience soreness or a dull ache. This can be treated with painkillers on the advice of your doctor.
If you have an incisional biopsy you will need stitches and a dressing.
How soon will I get my biopsy results?
How quickly you get the results of a biopsy will depend on the urgency of your case and the hospital where you had the procedure. Sometimes, your results will be available within a few days, but it can take longer.
Rarely, a muscle biopsy (sample of muscle tissue) will need to be taken when it’s suspected that SS has directly affected the muscles, but most patients won’t need one.
Unfortunately, muscle biopsy findings aren’t always specific, and a precise diagnosis may not be made.
Are there different types of muscle biopsy?
Yes, there are 2 types of muscle biopsy:
- Needle biopsy – a needle is inserted into the muscle to remove a small amount of muscle tissue.
- Open biopsy – a small cut is made into the skin and muscle to remove a larger sample of muscle tissue.
Will I need an anaesthetic?
The biopsy will normally be performed under local anaesthetic, but sometimes a general anaesthetic is needed.
Will I need stitches?
After a needle biopsy the wound is held together with sterile strips and a plaster, and no stitches are required.
After an open biopsy the incision is closed with stitches.
What happens next?
Depending on what type of biopsy you’ve had, and where the biopsy has been taken from, you may be able to go home from hospital on the same day or have to stay in overnight.
If an open biopsy has been taken from the leg you will need to rest it for the first day, and keep the wound dry for two days. A small amount of oozing from the wound is normal, but if there is excessive bleeding you should seek medical advice. Sports and excessive exertion should be avoided for at least 2 weeks. The stitches in your leg will be removed after 10 days.
When will I get my muscle biopsy results?
Results are usually available in a few weeks, but more sophisticated analysis may take months.
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