Cysts: what they are, when to worry and when to intervene

By Cristiano Antonino On Apr 4, 2023

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What is defined as a cyst is a cavity or sac, normal or pathological, enclosed by a membrane that contains liquid or semi-solid material

If the collection of liquid is not enclosed by membranes, it is called a pseudocyst.

In contrast, abscesses, infected collections containing pus, are different from cysts.

The shape of cysts is generally roundish and they may occur singly or in varying numbers and of different sizes.

Not all cysts are treated in the same way: they may disappear on their own or be surgically removed.

What is a cyst?

As already explained, a cyst is a closed sac or cavity lined by epithelium and filled with liquids, gas or semi-solid material; in the case where this accumulation is not lined by a distinct membrane, we cannot speak of a cyst but of a pseudocyst.

These sacs can develop in the most disparate locations and at any age, generally forming very quickly and then stopping their growth for good.

In some cases, it may happen that these abnormal formations shrink or continue to increase in size.

Cysts, in the vast majority of cases, are benign – they are therefore defined as dysfunctional.

There are, however, cases in which they can be spies of malignant tumours: there are, in fact, neoplasms with a cystic appearance, such as certain neoplasms of glandular origin.

Various types of cysts

As mentioned earlier, there are different types of cysts depending on where they develop.

Here is a list of them:

Dental cysts. Generally, dental cysts arise as a complication of pulpal necrosis, induced by trauma, deep caries or pulpitis, i.e. inflammation of the dental pulp. Depending on the nature of the contents or the site where they originate, there are many variations of dental cysts.
Chalazion. This is a disorder affecting the eyelids and is quite common. It derives from an inflammation of one or more Meibomian glands – those responsible for the lipid component of tears – which obstructs its excretory duct. It is fairly easily recognised, because it manifests itself with a swelling of the eyelid at the affected gland.
Ovarian cysts. These are sacs filled with liquid or solid material that form internally or externally to the ovaries.
Geodes, subchondral geodes or bony cysts. These are an important sign of arthrosis and other joint diseases, such as gouty arthritis. These are cystic spaces that form under the cartilage of the joints
Polycystic kidney. This is a genetic disorder in which normal kidney tissue is replaced by numerous cysts.
Baker’s cyst. This is a fluid-filled sac that forms behind the knee; this is why it is also known as a popliteal cyst. Its formation is most often caused by damage to the knee joint.
Sinus cysts. These are small formations that develop within the breast tissue. These lesions are quite common in perimenopausal women and sometimes occur in association with fibrocystic mastopathy.
Tendon cysts. A tendon cyst, or synovial cyst, is a swelling filled with synovial fluid that develops next to a joint or tendon.
Sebaceous cysts. An extremely common formation, the sebaceous cyst is benign in nature and forms under the skin, usually in a roundish shape. This lesion develops due to the occlusion of a sebaceous gland: sebum can no longer be disposed of and thus collects in a pouch.
Pilonidal cyst. A pilonidal cyst can also form in the skin. It almost always develops in the sacro-coccygeal region, just above the intergluteal groove. This sac may contain hair (hence the name pilonidal), but also sebaceous secretions, skin fragments, liquid or semi-solid material and other cellular elements. The appearance is that of a slight swelling.
Synovial ganglia or cysts. These are cystic swellings that develop particularly at the wrist, knee or back of the foot. They are often the result of joint inflammation, arthrosis or trauma: synovial fluid (hence synovial cyst) is pushed into the joint cavity, creating a sac. Inside the protuberances there is then a clear gelatinous fluid of high viscosity.
Bartolini’s cysts. These are round formations that develop in the vulvar region, inside the labia majora.
Liver cysts. They form in the liver parenchyma and can be of various types.
Dermoid cysts. This is called a benign tumour and is found particularly in the ovary, but can also arise in other locations, such as the kidneys, testicles and nervous system. The origin of cyst formation is embryonic: it derives from germ cells, which retain the ability to grow and differentiate into different tissue types. They do not normally cause discomfort unless they compress surrounding organs.

Cyst-like neoplasms

Also included in the category of cysts are neoplasms with a cystic appearance, i.e. malignant tumours that appear as cysts.

This is the case with:

adenoid cystic carcinoma, a malignant formation that predominantly affects adults and the elderly and is generally located in the trachea, salivary glands and breast.
neoplasms of the pancreas, which occur as a result of the out-of-control multiplication of cells in this organ.
ameloblastoma or keratocystic tumour, a usually benign neoplasm affecting the jaw bones.

Cystic fibrosis

In addition to malignant tumours, there are other diseases that can be related to cysts, such as cystic fibrosis: specifically, it is a degeneration in cyst development.

This disease is a genetic disorder whereby the cyst develops in the lung parenchyma, which then secretes mucus into the alveoli and results in reduced lung capacity, and is manifested by a persistent cough.

This disease is quite widespread: the number of patients surveyed in Italy exceeds 5000.

Diagnosis usually occurs at a very young age: the average age in Italy and Europe is 4.2 months, thanks also to neonatal screening, which involves more and more newborns; in 2016 – for example – it involved 83% of births.

Causes

It is not possible to identify an unambiguous cause for cysts.

The most common cysts are so-called retention cysts, i.e. cysts that are created by the obstruction of a glandular duct: this is the case with sebaceous cysts, which form in the sebaceous glands of the skin, often in the genital area or scalp area.

These formations, which can reach considerable size, contain the secretion product of the gland – sebum – which can become infected.

A cyst, however, can also form due to infectious processes, chronic inflammatory conditions, tumours, genetic diseases or during embryo-fetal development, such as dermoid cysts.

Symptoms

Being of great variety, not all cysts produce the same symptoms: some may have rather intense symptoms, while others are asymptomatic.

Obviously, everything is related to the size, whether it is one or several cysts, but also to the site of development.

For example, breast cysts tend to be larger and, although they are clearly palpable, are generally asymptomatic, harmless and present no danger: they are not malignant tumours and are unlikely to become so.

However, they are often removed because they can cause pain or a feeling of discomfort.

Diagnosis of cysts

Depending on the area of development and size, cysts can be seen with the naked eye or under a microscope, or be detectable by palpation.

Help, especially in cases where cysts cannot be seen directly, comes from imaging techniques such as X-rays, ultrasound scans, CT scans and MRI scans.

Cures and treatments for cysts

After a careful examination, the doctor will determine the treatment for a cyst.

Generally, if the sac is painful or causes discomfort to the patient – e.g. psychological due to an obvious cyst in the face – it is surgically removed, drained or aspirated via a needle or catheter.

If the cyst develops in internal organs, the operation is performed with the aid of imaging techniques.

More complex is the case when a malignant formation is suspected: in this case, a biopsy may be required before proceeding with removal to remove any doubt.

Anatomo-pathological tests may also be performed on a sample of internal fluid.

Finally, if there is a widespread presence of cysts as in the case of chronic diseases such as polycystic ovary, treatment will be directed at the causes of their origin.

In this case, an attempt will be made to reduce their formation by means of oestrogen therapy.

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