A cyst is a sac-like structure within the body, distinct from surrounding tissues, that can be filled with various materials like fluid, air, or semi-solid substances. These formations are quite common and can develop in nearly any part of the body, including organs, bones, or under the skin. Cysts vary significantly in size, ranging from microscopic to large enough to displace internal organs. While they are typically benign, their presence often prompts investigation, especially if they cause discomfort or other symptoms.
What is Cyst Fluid Made Of?
The composition of cyst fluid is diverse, largely depending on the cyst’s type and its location within the body. Commonly, cyst fluid is primarily water, serving as a medium for other components. It often contains proteins, which can vary in type and concentration, and dead cells shed from the cyst lining or surrounding tissues.
Metabolic waste products, byproducts of cellular processes, are also frequently found in cyst fluid. Sometimes, the fluid may contain blood, indicating a hemorrhagic cyst, or pus, suggesting an infection. For example, epidermoid cysts are filled with keratin, a protein that forms skin, hair, and nails, along with cellular debris. Sebaceous cysts are filled with sebum, an oily substance produced by glands in the skin.
Common Reasons Cysts Contain Fluid
Cysts form and accumulate fluid through several general mechanisms, often arising from disruptions in normal bodily processes. One common reason is the blockage of ducts or openings, which can lead to a buildup of secretions. For instance, sebaceous cysts can develop when sebaceous glands or their ducts, responsible for producing skin oil (sebum), become damaged or obstructed, causing sebum to accumulate. Similarly, a Bartholin’s cyst forms if the ducts of the Bartholin glands in the vagina become blocked.
Inflammation or infection can also trigger cyst formation. A pilonidal cyst, common in the lower back, can become infected and fill with fluid or pus, often due to an ingrown hair. Trauma or injury to tissue may also lead to cyst development by pushing skin cells deeper into the skin layers, creating a pocket where substances like keratin can collect. Developmental abnormalities can also result in cysts, such as arachnoid cysts, which are pockets of cerebrospinal fluid that form during fetal brain development.
How Cyst Fluid is Analyzed
When a cyst is identified, particularly if it’s causing symptoms or its nature is unclear, healthcare providers may recommend fluid aspiration. This procedure involves using a fine needle to draw out fluid from the cyst, often guided by imaging techniques like ultrasound to ensure precise needle placement. The fluid is then sent to a laboratory for analysis.
One primary analysis is cytological examination, where cells within the fluid are examined under a microscope. This helps identify cell types, look for signs of inflammation, infection, or abnormal cells that might indicate malignancy. For example, in pancreatic cysts, cytology helps differentiate between benign, inflammatory, or cancerous cells. Biochemical tests also measure fluid markers. For pancreatic cysts, levels of carcinoembryonic antigen (CEA) and amylase are often checked to help distinguish between mucinous and non-mucinous cysts, with CEA levels above 192 ng/mL often indicating a mucinous cyst. Molecular analyses, such as testing for KRAS gene mutations, can provide further information, particularly for pancreatic cysts, aiding in the diagnosis and risk assessment.
What Happens After Fluid Analysis?
Following cyst fluid analysis, next steps depend on results and symptoms. Draining the fluid during aspiration can be both a diagnostic tool and a therapeutic measure, often relieving discomfort by reducing pressure. If the fluid is clear and the cyst collapses completely, and the analysis confirms it is benign, further intervention may not be necessary.
If the analysis reveals signs of infection, such as pus or bacterial markers, antibiotics may be prescribed. For cysts that are symptomatic, recurring, or show concerning features in the fluid analysis, such as suspicious cells or elevated tumor markers, surgical removal of the cyst may be recommended. Doctors typically schedule a follow-up visit, often within 4 to 6 weeks, to ensure the cyst has not refilled and to discuss any management plans.