Cysts

Cysts are closed sacs or cavities that can form in any tissue of the body. They are typically filled with fluid, air, or semi-solid material and are often lined by epithelium; those that lack a proper lining are termed pseudocysts. Cysts can vary greatly in size from millimeters to several centimeters and may be solitary or multiple. Most cysts are benign and cause no symptoms, but they can produce pain, swelling, obstruction, or cosmetic concerns if they grow large or press on nearby structures. Complications can include infection, rupture, hemorrhage, or impaired function of nearby organs.

Common cysts occur in various organs. Skin cysts, such as epidermoid and pilar cysts, often arise on the scalp, face, or trunk and may become inflamed. Ovarian cysts are common in women of reproductive age and include functional cysts (follicular or corpus luteum) as well as other types; most resolve without treatment, but persistent or complex cysts may require evaluation or surgery. Renal cysts are frequently simple and benign, especially in older adults, while polycystic kidney disease involves multiple cysts and is hereditary. Liver cysts can be simple and asymptomatic or part of a broader disease. Cysts can also arise in the brain (such as arachnoid cysts), pancreas, or other organs.

Diagnosis usually relies on clinical evaluation combined with imaging, most commonly ultrasound. CT or MRI may be used for further detail, and fluid aspiration or biopsy can help determine the cyst’s contents and nature if the diagnosis is uncertain.

Management ranges from observation for asymptomatic, simple cysts to intervention for symptomatic or complex cysts. Options include aspiration, sclerotherapy, or surgical removal, and treatment of underlying conditions or infection when present.