areas where clothing rubs them. The resulting
SCARmay require PLASTIC SURGERYfor 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 alsoGENETIC 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 SKINand
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 alsoMACULE; PAPULE; PUSTULE.
onychomycosis A common fungal INFECTION,
typically CANDIDIASISor 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 dis-
comfort 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 walk-
ing, 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 appear-
ance 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 treat-
ment affords the most successful results.
See also ANTIFUNGAL MEDICATIONS; INGROWN NAIL;
PARONYCHIA; PSORIASIS.onychomycosis 179