Cysts

A cyst is a closed sac having a distinct membrane and division on the nearby tissue. It may contain air, fluids, or semi-solid material. A collection of pus is called an abscess, not a cyst. Once formed, a cyst could go away on its own or may have to be removed through surgery.

Locations

• Acne cyst – Pseudocysts associated with cystic acne. Actually an inflammatory nodule with or without an associated epidermoid inclusion cyst.
• Arachnoid cyst (between the surface of the brain and the cranial base or on the arachnoid membrane)
• Baker's cyst or popliteal cyst (behind the knee joint)
• Bartholin's cyst
• Breast cyst
• Chalazion cyst (eyelid)
• Colloid cyst
• Crain's backs
• Cysticercal cyst (the larval stage of Taenia sp.)
• Dentigerous cyst (associated with the crowns of non-erupted teeth)
• Dermoid cyst (ovaries, testes, many other locations from head to tailbone)
• Epididymal cyst (found in the vessels attached to the testes)
• Ganglion cyst (hand/foot joints and tendons)
• Glial cyst (in the brain)
• Gartner's duct cyst (vaginal or vulvar cyst of embryological origin)
• Hydatid cyst (larval stage of Echinococcus granulosus (tapeworm))
• Keratocyst (in the jaws, these can appear solitary or associated with the Gorlin-Goltz or Nevoid basal cell carcinoma syndrome. The latest World Health Organization classification considers Keratocysts as tumors rather than cysts)
• Liver cystic disease
• Meibomian cyst (eyelid)
• Mucoid cyst (ganglion cysts of the digits)
• Nabothian cyst (cervix)
• Ovarian cyst (ovaries, functional and pathological)
• Paratubal cyst (fallopian tube)
• Periapical cyst (The periapical cyst, otherwise known as radicular cyst, is the most common odontogenic cyst.)
• Peritoneal cyst (lining of the abdominal cavity)
• Pilar cyst (cyst of the scalp)
• Pilonidal cyst (skin infection near tailbone)
• Renal cyst (kidneys)
• Polycystic ovary syndrome
• Pineal gland cyst
• Radicular cyst (associated with the roots of non-vital teeth, also known as Periapical cyst)
• Testical cyst
• Sebaceous cyst (sac below skin)
• Tarlov cyst (spine)
• Trichilemmal cyst – Same as a pilar cyst. A familial cyst of the scalp.
• Vocal fold cyst

Cystic fibrosis

Despite being described in 1938 as involving the microscopic appearance of cysts in the pancreas, cystic fibrosis is an example of a genetic disorder whose name is related to fibrosis of the cystic duct and does not involve actual cysts.

Benign vs malignant

Many cysts in the body are benign (functional), the result of plugged ducts or other natural body outlets for secretions. However, a few are tumors or are produced within tumors, and are potentially malignant:

• Dermoid cyst
• Keratocyst