A closed sac or capsule like structure, filled with semisolid, liquid or gaseous content that resembles a blister, is called as cyst. Cyst can occur in any tissue of the body parts and may vary from microscopic size to sport ball size. Cyst may be visualized only using a microscope, or can grow so big that it becomes capable of displacing the tissues and internal organs.
Cyst is not the usual part of the tissue, in which it appears. It comprises a distinct membrane around it that separates it from the surrounding tissue, called as the cyst wall or capsule. If sac is filled with pus, then it is not considered as cyst, but it is an abscess.
Important Causes of Cysts
Cysts may arise as a result of various processes of the body that includes infections, genetic conditions, wear and tear to the regular fluid flow, tumors, parasites, defective cells, impact injury causing vessel breakage, defects in development of organs in an embryo and chronic inflammatory conditions.
Benign and Malignant Cysts
Majorily the cysts are of benign nature, generally caused due to plugged ducts or blockage of other outlets of secretions in the body. Some cysts are tumurous, which are formed inside the tumors and can become potentially malignant like dermoid or kerato cysts.
Different Types of Cysts and Their Causes
The skin epidermis is made from thin, protective cells layers that are continuously shed by the body. When the surface cells instead of exfoliating, gets deeper into the skin and forms a lump containing thick and greasy content, it gives rise to sebaceous or epidermoid cysts. These cysts are more observed in areas with little hair follicles and large sebaceous glands like neck, face, groin and back.
The epidermal cells make the cyst wall, and the keratin protein gets secreted inside it, which at times, drains out of the cyst as a thick yellow substance.
Ovarian cysts are majorily of benign form and some get so large that one may feel the woman is pregnant. Ovarian cyst of size 5 cm or less, are common in women during their reproductive years. Around 20% of women suffer from ovarian cyst or tumor at some point in their life and in small percentage it is diagnosed to be due to ovarian cancer. Biomarkers (Specific proteins) known to be responsible for ovarian cancer are HE4 and CA 125.
Several forms of cysts may appear in kidneys and few may be present from birth. Some kidney cysts are caused due to blockage of renal tubules, whereas, in patients of kidney vascular disease, cysts are formed as a result of dilatation of blood vessels. Solitary cysts formed may contain blood along with other fluids.
Two major forms of cysts may appear during teeth formation. Periapical cyst is the most commonly occurring odontogenic (teeth formation and development) cyst, caused by dental caries, pulp death and inflammation of the pulp. The second form is the dentigerous cyst that is formed around the crown of unerupted tooth.
The brain is protected by the arachnoid membrane but during foetal development, at times the arachnoid membrane splits up and doubles, forming an abnormal sac in the cerebrospinal fluid called as arachnoid cyst. These cysts need to be drain off in affected newborns.
When a person experiences a tightness or bulge behind the knee, it could be probably due to baker’s cyst or popliteal cyst formation. This cyst causes pain on physical activity that includes knee extension. It is caused by a problem of the knee joint like cartilage tears or knee arthritis.
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