Webster's New World Medical Dictionary

matter, gray
See 
gray matter.
matter, white
See 
white matter.
maxilla
The major bone of the upper jaw.
MCAT
Medical College Admissions Test.
McBurney point
The most tender area of the
abdomen of patients in the early stage of
appendicitis.
McCune-Albright syndrome
See 
polyostotic
fibrous dysplasia.
MD
Abbreviation for the Latin 
Medicinae Doctor,
“doctor of medicine.”
mean cell hemoglobin
See 
CBC.
mean cell hemoglobin concentration
See
CBC.
mean cell volume
See 
CBC.
measles
An acute and highly contagious viral dis-
ease characterized by fever, runny nose, cough, red
eyes, and a spreading skin rash. Measles can be
complicated by ear infections, pneumonia,
encephalitis (which can cause convulsions, mental
retardation, and even death), the sudden onset of
low blood platelet levels with severe bleeding (acute
thrombocytopenic purpura), or a chronic brain dis-
ease that occurs months to years after an attack of
measles (subacute sclerosing panencephalitis).
During pregnancy, exposure to the measles virus
may trigger miscarriage or premature delivery.
Treatment includes rest and use of anti-itching
preparations to soothe the skin, and nonaspirin
pain relievers for fever. Measles is a leading cause of
vaccine-preventable death worldwide. Also known
as rubeola, hard measles, seven-day measles, eight-
day measles, nine-day measles, ten-day measles,
and morbilli. See also 
measles, atypical; measles
encephalitis; measles immunization.
measles, atypical
An altered type of measles that
may begin with a mild prodrome of fever,
headache, cough, and abdominal pain. In other
cases, a sudden onset of high fever, headache, and
chest pain occur. The rash appears 1 or 2 days later,
often beginning on the limbs. Some patients become
severely ill. It occurs in people who were given the
old killed-virus measles vaccine between 1963 and
1967, which did not provide complete immunity, or
in those who received improperly stored (weak-
ened) live virus vaccine after 1967.