cyst

A cyst is a closed, sac-like structure that can contain fluid, air, or semi-solid material. It is usually lined by a membrane or epithelium. Cysts can arise in nearly any organ or tissue and may be congenital or acquired. When the lining forms a true epithelium, the cyst is called a true cyst; when the wall lacks epithelial lining, it is referred to as a pseudocyst or nonepithelial cyst.

Subtypes include cutaneous cysts such as epidermoid and sebaceous (pilar) cysts, and ganglion cysts near joints or tendons. Ovarian cysts (follicular, corpus luteum) are common in reproductive-age women. Renal, hepatic, and pancreatic cysts occur in their respective organs. Cysts may form after infections, inflammation, trauma, ductal obstruction, or as developmental remnants.

Most cysts are asymptomatic and discovered incidentally. When symptoms occur, they may include a palpable lump, swelling, or pain if the cyst is large, infected, or compresses nearby structures. Diagnosis relies on imaging such as ultrasound, which distinguishes cystic from solid masses, with CT or MRI used for further evaluation. Fluid aspiration or histologic examination may be needed to confirm the diagnosis and exclude neoplasia.

Management ranges from observation to intervention. Simple, asymptomatic cysts are often monitored. Symptomatic or enlarging cysts may be drained or surgically excised; some cysts respond to sclerotherapy. Ovarian cysts require individualized management based on size, symptoms, age, and malignancy risk. The overall prognosis is favorable, but recurrence can occur, and complications include infection, rupture, or hemorrhage.

Cysts are common across populations, with skin cysts among the most frequent lesions. Renal and hepatic cysts increase with age, while ovarian cysts are prevalent in women of reproductive age.