A cyst is a closed, sac-like structure defined by a distinct membrane that separates it from surrounding tissue. Inside this pocket is a liquid or semi-solid substance known as cystic fluid. Cysts are common and can develop from infections, clogged glands, or as a defensive response by the body. While the presence of a cyst can be concerning, the vast majority are benign and not cancerous.
What Cystic Fluid is Made Of
The composition of cystic fluid varies depending on the cyst’s location and cause. The fluid contains proteins, electrolytes, and various enzymes. It can also hold hormones, particularly in cysts related to glandular tissues like the ovaries or thyroid.
Cellular debris, consisting of dead cells shed from the cyst’s lining, is also a component. In some cases, the fluid contains specialized substances produced by the nearby cells. For instance, sebaceous cysts are filled with sebum, the natural oil produced by glands in the skin.
Appearance and Types of Cystic Fluid
The visual characteristics of cystic fluid, such as its color and consistency, offer preliminary information about a cyst. When a sample is taken, its appearance helps guide diagnostic steps.
- Serous fluid is thin, watery, and clear or straw-colored. This type of fluid is often found in simple cysts that are benign.
- Sebaceous fluid is thick, oily, and has a whitish or yellowish appearance, resembling cheese. This material, known as keratin, is characteristic of cysts from blocked hair follicles or skin glands.
- Hemorrhagic fluid appears red, pink, or brown. This coloration indicates the presence of blood, which may have entered the cyst due to minor bleeding or injury.
- Purulent fluid is opaque, thick, and possibly foul-smelling. This fluid, commonly known as pus, is a sign of infection within the cyst.
How Doctors Analyze Cystic Fluid
To determine the nature of a cyst, a fluid sample is collected and analyzed using a procedure called Fine-Needle Aspiration (FNA). A doctor uses a thin, hollow needle to withdraw fluid from the cyst. This process is often performed with the guidance of medical imaging, such as an ultrasound, to ensure accurate placement for cysts that are deep or not easily felt.
Once collected, the sample is sent to a laboratory for evaluation by a pathologist. The primary analysis is cytopathology, which involves examining the fluid under a microscope to study the cells it contains. The pathologist looks at the number and types of cells, their shape, size, and arrangement.
The fluid may also undergo biochemical tests to measure levels of specific proteins, enzymes, or hormones. If an infection is suspected, a portion of the fluid is cultured. This involves placing the sample in a special medium to see if bacteria or other microorganisms grow, which would confirm an active infection.
What the Analysis Reveals
The laboratory analysis of cystic fluid provides detailed information about the cyst’s origin and potential health implications. A primary goal of this examination is to distinguish between a benign and a malignant condition. By studying the cells from the fluid, a pathologist can identify any abnormal or cancerous cells.
The analysis is also definitive in confirming an infection. The identification of bacteria, along with a high concentration of white blood cells in the fluid, signals that the cyst is infected or is an abscess. This finding directs treatment toward resolving the infection, often with antibiotics.
Furthermore, the specific characteristics of the cells can help pinpoint the cyst’s origin. For example, cells found in an ovarian cyst look different from those in a thyroid or breast cyst. This information helps in understanding why the cyst formed and guides any necessary follow-up care.