Skin cysts – should I be worried?

Written by: Mr Alastair MacKenzie Ross
Edited by: Cal Murphy

Cysts can come in all shapes and sizes and can appear all over the body. What are these strange lumps? Should you be worried about them? What are the differences between them? Leading plastic surgeon Mr Alastair MacKenzie Ross lends us his insight into the world of skin cysts.

What are the most common types of cyst?

The most common types of cysts vary according to the part of the body, but in normal skin, the most common cysts are epidermal or epidermoid cysts. These are often inappropriately referred to as “sebaceous cysts”; however, this is actually a misnomer (true sebaceous cysts are different and much less common). Epidermal cysts form when cells at the surface of the skin (epidermis) move deeper into the skin instead of shedding off. These cells produce a protein called keratin, which helps to strengthen and protect the surface of the skin; however, when the cells have moved deeper into the skin and continue to divide and multiply, the keratin they secrete becomes trapped in the middle of the sac of cells, appearing as a thick, yellowish, ‘cheesy’, substance, which may leak from the cyst if it is burst.

It can be difficult to tell the difference between an epidermal cyst and a lipoma (another common swelling under the skin made of fat tissue). However, it should be possible to see and feel where the cyst is attached to the skin – there is usually a small punctum or indent.

You can also get cysts is the scalp; however, they are not actually attached to the skin, but are almost free-floating, attached to hair follicles. These are called pilar or trichilemmal cysts.

A third form of common cysts are around the finger, toe or wrist joints. These are called ganglion cysts (referring to out-pouching of a joint), and are also commonly known as mucous cysts on the last joints towards the ends of finger or toes. Here, the joint lining moves to where it shouldn’t be.

Cysts can appear in other places, e.g. around the eye, and the lips.


Do they all look the same?

It depends on where they are. For example, finger cysts look different from cysts elsewhere on the skin. That said, many cysts can look similar.

Epidermal cysts can change appearance if they get infected – they become very red, painful, and hot. When this happens, they can become difficult to distinguish from an abscess. The cyst may split, and a cheesy material come out. Infections usually respond to antibiotics. After a treated infection the cyst become infected again. This is a reason to have it removed.


Can cysts be cancerous?

They can, but it’s very unusual. You can also have cancers that look like cysts – lumps under the skin can look like cysts but are actually cancer.


Are there any types of cyst that can be dangerous if not treated?

If it’s a proper cyst, it’s unlikely to be dangerous. However, cysts can grow. Some big cysts, especially in awkward places, such as around the eye, can cause pressure.

If cancer is mistaken for a cyst and left untreated, it can be dangerous – you should always have it checked to make sure it’s a cyst rather than just assuming it is.

By Mr Alastair MacKenzie Ross
Plastic surgery

Mr Alastair MacKenzie Ross is one of London's leading consultant plastic surgeons. He specialises in skin cancer (including melanoma), electrochemotherapy, reconstruction and scars.

Mr Mackenzie Ross qualified in medicine from the University of Cambridge in 1996 and went on to complete his higher surgical training in London. He undertook a hand surgery fellowship in Singapore in 2010 and the following year returned to London to complete a cosmetic reconstructive surgery interface fellowship. In 2012, he was awarded a further prestigious fellowship in melanoma and surgical oncology at the Melanoma Institute Australia. He is a core member of the multi-disciplinary teams for melanoma and non-melanoma cancer at Guy's and St Thomas' Hospitals, and a founding member of the multi-disciplinary skin cancer team at the Wellington Hospital. Additional to his work within the NHS, Mr MacKenzie Ross sees private patients at the OneWelbeck clinic.

Mr Mackenzie Ross’ many years of clinical experience along with his strong academic background make him a leading expert in the field of plastic surgery. He was formerly the surgical lead for the London Cancer Alliance Skin Cancer Pathway Group and has teaching and training responsibilities in his role of clinical supervisor within Guy’s and St Thomas’ Hospitals. His academic work is widely published in peer-reviewed journals.

In keeping with best practice, skin cancer patients under Mr MacKenzie Ross’ care are managed with the benefit of input from the whole multi-disciplinary team. Electrochemotherapy is at the cutting-edge of cancer management and Mr MacKenzie Ross is one of the first to offer this treatment privately in London.

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