An anechoic cyst is a type of cyst that contains a low-density substance, which appears black on an ultrasound. These cysts are usually filled with fluid, or in the case of pulmonary cysts, gas.
They are called anechoic because they do not produce an echo during an ultrasound examination. These cysts can develop in various areas of the body, such as the breasts, ovaries, or thyroid, and they are typically well-defined and considered benign.
Anechoic cysts are often detected during routine medical exams and usually do not cause symptoms. Depending on the cyst's size, location, and contents, they can sometimes lead to discomfort or pain. In many cases, anechoic cysts will resolve on their own without the need for treatment.
Main characteristics
The key features of a simple anechoic cyst include:
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Fluid-filled interior;
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Smooth, well-defined edges;
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Oval or rounded shape;
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No solid content;
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Benign lesion;
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Appears dark or black on ultrasound.
Unlike simple anechoic cysts, complex anechoic cysts have irregular walls and may contain additional structures inside, creating separate spaces.
These cysts can also hold solid materials or a mixture of solid and liquid substances, making them more worrisome.
Different types
The main types of anechoic cysts are:
1. Anechoic cyst in the ovary
Anechoic ovarian cysts can form inside or on the surface of the ovaries, often due to normal hormonal changes during the menstrual cycle or pregnancy. They can also occur as a result of using hormonal medications like birth control pills.
Most of these cysts are simple or functional, such as follicular cysts or corpus luteum cysts, and are benign, often resolving on their own.
Generally, anechoic ovarian cysts do not cause symptoms. However, if they persist or grow, they can lead to pelvic pain, changes in menstrual cycles, or difficulty conceiving. Learn more about ovarian cyst symptoms.
2. Anechoic cyst in the breast
Anechoic cysts in the breast are relatively common and usually result from fluid buildup in the mammary glands, often due to hormonal changes during the menstrual cycle.
These cysts are typically benign and are most frequently found in women of reproductive age (15 to 50 years old). They can also appear in postmenopausal women, particularly those undergoing hormone therapy.
While most anechoic breast cysts are simple, some can be more complex. Read more about breast cysts.
3. Anechoic cyst in the kidney
Anechoic cysts in the kidneys can be either simple or complex. In most cases, they do not cause symptoms and simply require monitoring by a healthcare provider.
However, these cysts may become infected, bleed, or grow to a large size, resulting in symptoms such as back pain, pelvic or abdominal discomfort, fever, or blood in the urine.
When cysts are present in multiple numbers, such as in polycystic kidney disease, they can lead to loos of kidney function or even kidney cancer. These cases require medical treatment.
4. Anechoic cyst in the liver
Anechoic cysts in the liver can be congenital (present from birth) or acquired later in life due to trauma, inflammation, or infections like tapeworms. These cysts usually do not cause symptoms and often regress on their own. See cyst on liver.
If the cysts grow significantly or block bile ducts, they may cause symptoms such as abdominal pain or jaundice, which may require drainage or surgery for treatment.
5. Anechoic cyst in the thyroid
Anechoic cysts in the thyroid are typically not harmful and do not cause symptoms. It is generally recommended to monitor the cyst to see if it changes in size or characteristics over time.
However, if the cyst becomes large, it could lead to symptoms like difficulty swallowing or breathing, or the development of a palpable lump in the neck.
Concerning signs
An anechoic cyst may become a concern if:
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It grows over time, causing symptoms;
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It obstructs the bladder, kidneys, or bile ducts;
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It becomes infected, increasing the risk of abscesses;
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It has a high risk of rupture, such as ovarian or kidney cysts;
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It is associated with genetic conditions, such as polycystic kidney disease.
While most anechoic cysts are benign, in rare instances, they can become malignant (cancerous), particularly when they are complex and contain solid material or other internal walls.
Treatment options
The primary treatments for an anechoic cyst include:
1. Regular medical follow-up
For small, asymptomatic anechoic cysts, regular medical monitoring ("watchful waiting") is recommended. This allows healthcare providers to track whether the cyst shrinks or grows and to assess its characteristics through ultrasound or other imaging methods.
2. Cyst drainage
If an anechoic cyst is large or causing symptoms, drainage may be necessary. The drained fluid is sent to the lab to determine whether the cyst is benign or if it could be cancerous. A biopsy may also be performed in these cases.
3. Surgery
Surgery may be needed to remove an anechoic cyst, particularly in the case of complex cysts that are symptomatic or raise concerns for malignancy (cancer).
The treatment approach depends on the cyst’s type, symptoms, growth rate, and other characteristics.