Moles, the medical term being Nevi, vary in color from
yellow-brown to black. They may be small or large; flat or
raised; smooth, hairy, or verrucous; and have a broad or
Moles may rarely undergo malignant change and become
malignant melanomas. They may be separated into groups
according to their propensity to become malignant; in many
instances, clinical and histologic appearances can be
correlated. Though this classification is practical, it is
not invariably reliable. About 25% of malignant melanomas
do not develop from a preceding mole.
Intradermal nevi (common moles), in which the malanocytes
are found in the corium - not in the epidermis - are
benign. Hairy mores are usually intradermal and are not
precursors of melanomas.
Junctional nevi may be flat or raised; the melanocytes are
found at the junction of the dermis and epidermis. Though
more susceptible to activation, only a small percentage
Active functional nevi contain some changed cells
characteristic of early or premalignant lesions. Melanomas
not infrequently develop from this type of nevus. Clinical
evidence which reflects possible malignant changes includes
increased size or pigmentation of moles.
Childhood nevi are usually flat and initially of the
junctional type, becoming intradermal subsequently.
Histologic examination may show changes characteristic of
benign juvenile melanoma, but malignant melanoma is rare
before puberty. The decision to remove a pigmented nevus
need not be made until the child reaches age 9 or 10.
Pigmented nevi are commonly confused with freckles.
Excision by a specialist of all malignant or suspected
lesions is indicated. Histologic examination is mandatory.
Many nevi are removed for purely cosmetic reasons and in
these cases excision need not be wide. Excision is
recommended when a pigmented nevus shows increasing
pigmentation, redistribution of color or a halo of pigment
around the base, or when any nevus increases in size,
bleeds, ulcerates or crusts.
In general, malignant melanomas develop more readily from
moles on the lower legs and on the mucous membranes than
from lesions located elsewhere. It frequently has been
emphasized that pigmented moles subjected to constant
irritation or trauma show a relatively high incidence of
malignant changes, and should be removed. Clinical judgment
is to be exercised.