| umbilical cyst | A small red sessile or pedunculated tumour at the umbilicus in an infant; it is due to the persistence of a segment of the vitellointestinal duct. Synonym: umbilical cyst. (05 Mar 2000) |
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| unicameral bone cyst | A unilocular cyst containing serous fluid and lined with a thin layer of connective tissue, occurring usually in the shaft of a long bone in a child. Synonym: idiopathic bone cavity, osteocystoma, simple bone cyst, traumatic bone cyst, unicameral bone cyst. (05 Mar 2000) |
| unicameral cyst | A cyst having a single sac. Synonym: unicameral cyst. (05 Mar 2000) |
| unilocular cyst | A cyst having a single sac. Synonym: unicameral cyst. (05 Mar 2000) |
| unilocular hydatid cyst | The commonest form of hydatid cyst in man, caused by Echinococcus granulosus and found in the liver, lungs, or any other site where the hexacanth embryo may settle if it passes the hepatic or pulmonary capillary filters; characterised by large balloon-like forms lined internally with a germinative membrane, enclosed externally in a laminated membrane within a host-parasite capsule, and filled with fluid (hydatid fluid) and infectious scoleces of the young tapeworms (hydatid sand). (05 Mar 2000) |
| Klestadt's cyst | A soft tissue cyst located near the attachment of the ala over the maxilla; probably derived from the lower anterior part of the nasolacrimal duct. Synonym: Klestadt's cyst, nasolabial cyst. (05 Mar 2000) |
| urachal cyst | Cyst occurring in a persistent portion of the urachus, presenting as an extraperitoneal mass in the umbilical region. It is characterised by abdominal pain, and fever if infected. It may rupture, leading to peritonitis, or it may drain through the umbilicus. (12 Dec 1998) |
| urinary cyst | A cyst containing extravasated urine. (05 Mar 2000) |
| utricular cyst | Dilatation of the utricular lumen; usually unilocular. (05 Mar 2000) |
| fissural cyst | A cyst derived from epithelial remnants entrapped along the fusion line of embryonal processes. Synonym: inclusion cyst. (05 Mar 2000) |
| lacteal cyst | A retention cyst in the mammary gland resulting from closure of a lactiferous duct. Synonym: milk cyst. (05 Mar 2000) |
| follicular cyst | <physiology> Cyst due to the occlusion of the duct of a follicle or small gland. (12 Dec 1998) |
| lateral periodontal cyst | An intraosseous cyst, usually encountered in the cuspid-premolar region of the mandible, derived from the remnants of the dental lamina and representing the intraosseous counterpart of the gingival cyst. (05 Mar 2000) |
| leptomeningeal cyst | <radiology> Growing skull fracture, trauma most likely to be , skull fracture with tear of dura, herniation of fluid-filled arachnoid tissue, cyst walled off by subarchnoid adhesions, XR: oval area of bony erosion with scalloped margins, may result in acquired encephalocele (12 Dec 1998) |
| liver cyst | <radiology> Simple cyst, polycystic liver disease (50% most likely to be renal cysts), abscess (pyogenic, amebic, hydatid), traumatic haematoma, Caroli disease, cystic hepatoblastoma, cystadenoma / cystadenocarcinoma, haemangioendothelioma, cystic metastasis (uncommon): sarcoma, melanoma, ovarian cystadenocarcinoma (12 Dec 1998) |