Dictionary

xanthoma tendinosum Xanthoma that clusters around tendons and is associated with lipid disorders, including chronically elevated blood cholesterol levels.

xanthoma tuberosum Xanthoma that clusters near joints and is associated with lipid disorders, cirrhosis of the liver, and thyroid disorders.

xanthomatosis An accumulation of excess lipids in the body that is due to disturbance of lipid metabolism and marked by the formation of xanthomas. See also xanthoma.

xanthopsia A form of chromatopsia, a visual abnormality in which objects look as though they have been overpainted with an unnatural color. In xanthopsia, that color is yellow.

xanthosis Yellowing of the skin without yellowing of the eyes, as is seen in jaundice.

XDR-TB See tuberculosis, extensively drugresistant.

xenotransplantation Transplantation from one species to another (for example, from a baboon to a human).

xero- Prefix indicating dryness, as in xeroderma (dry skin).

xeroderma Abnormally dry skin. Xeroderma can be caused by a deficiency of vitamin A, systemic illness (such as hypothyroidism or Sjogren’s syndrome), overexposure to sunlight, and medication. Xeroderma can usually be addressed with the use of over-the-counter topical preparations.

whooping cough See pertussis.

Wilms tumor A childhood form of kidney cancer with a peak age of occurrence at 3 years of age. It is sometimes associated with abnormalities of the urinary tracts or other birth defects. Some cases are related to defects in one of two genes referred to as Wilms’ tumor 1 (WT1) or Wilms’ tumor 2…

Wilson disease An inherited disorder of copper metabolism that results in an abnormal accumulation of copper in the body. Although the accumulation of copper begins at birth, symptoms of the disorder do not appear until later in life, between the ages of 6 and 40. A diagnostic feature of the disease is a Kayser-Fleischer ring,…