Webster's New World Medical Dictionary

keratosis, seborrheic
A common skin disorder
that is characterized by benign, painless, often 
wart-like skin lesions that appear to be “stuck on.”
The raised spots are usually yellow or brown.
Treatment, if warranted, involves surgical or cryo-
surgical removal. Also known as seborrheic warts
and verruca.
keratosis, senile
See 
keratosis, actinic.
keratosis, solar
See 
keratosis, actinic.
keratosis follicularis
A genetic skin disease
that is characterized by slowly progressive harden-
ing of the skin (keratosis) around the hair follicles.
This disorder is inherited in an autosomal dominant
manner and is due to mutation in a gene called
ATP2A2 on chromosome 12. Also known as Darier
disease.
keratotic scabies
See 
scabies, keratotic.
keratotomy
A surgical cut of the cornea.
keratotomy, radial
A surgical procedure
designed to flatten the cornea and thereby correct
nearsightedness (myopia). It is called a radial ker-
atotomy because the radial incisions in the cornea
resemble the spokes in a bicycle wheel.
kernicterus
A disorder that is due to severe jaun-
dice in the newborn, with deposition of the pigment
bilirubin in the brain that causes damage to the
brain, potentially leading to athetoid cerebral palsy,
hearing loss, vision problems, or mental retardation.
Also known as bilirubin encephalopathy.
Kernig sign
A sign indicating the presence of
meningitis (inflammation of the meninges covering
the brain and spinal cord). The test for Kernig sign
is done by having the person lie flat on the back, flex
the thigh so that it is at a right angle to the trunk,
and completely extend the leg at the knee joint. If
the leg cannot be completely extended due to pain,
this is Kernig sign.
Keshan disease
A condition caused by deficiency
of the essential mineral selenium. Keshan disease is
a potentially fatal form of cardiomyopathy (disease
of the heart muscle). It was first observed in Keshan
province in China, and it has since been found in
other areas where the selenium level in the soil is
low. Treatment involves selenium supplementation.