Encyclopedia of Health and Medicine

onychomycosis 179
areas where clothing rubs them. The resulting
SCAR may require PLASTIC SURGERY for the desired
cosmetic appearance, depending on the size,
nature, and location of the nevus. Small nevi heal
without noticeable scarring. Nevi do tend to recur
after removal.
See also GENETIC DISORDERS; MELANOCYTE; PARKIN-
SON’S DISEASE; SKIN SELF-EXAMINATION; VITILIGO.
nodule A small cluster of cells that arises from
the subcutaneous or dermis layer of the SKIN and
forms a swelling. Nodules are solid and distinct
from the surrounding tissue. Most skin nodules
arise from causes other than dermatologic, such as
neurofibroma and LIPOMA. Nodules may exist in
other parts of the body, typically as symptoms of
systemic disease.
See also MACULE; PAPULE; PUSTULE.
onychomycosis A common fungal INFECTION,
typically CANDIDIASIS or TINEA, of the fingernail or
toenail. The infection causes the nail to thicken,
discolor, fragment, and peel or crack. Though
some people experience itching, PAIN, or other discomfort
with onychomycosis, most people seek
medical care because of the nail’s appearance.
Onychomycosis affects the structure and function
of the nail, however. Onychomycosis affecting
multiple toenails can interfere with proper walking,
and onychomycosis of the fingernails may
reduce gripping ability and the ability to perform
tasks such as typing or keyboarding. The doctor
often can make the diagnosis based on the appearance
of the NAILS, though may choose to examine
tissue samples under the microscope to confirm
the presence of the infective FUNGUS.
Eradication of the fungus often requires oral
antifungal medication in combination with topical
antifungal medication. Onychomycosis can be a
stubborn infection, making several courses of
treatment necessary. Early diagnosis and treatment
affords the most successful results.
See also ANTIFUNGAL MEDICATIONS; INGROWN NAIL;
PARONYCHIA; PSORIASIS.