Dr
Margaret answers e-mailers' embarrassing problems in
this biweekly problem page.
Pigmentation
Dear Dr Margaret
Under my arms and between my legs the skin is very much
darker than elsewhere on my body. This is very embarrassing
in the summer when I am swimming. What is it and how can
I deal with it?
Dear
Dr Margaret
Is it abnormal for a female to have much darker skin around
the private area? Does it mean something is wrong?
It
is perfectly normal for the skin under the arms and between
the buttocks (and around the vagina in women) to be darker
than elsewhere on the body. So usually it does not mean
that anything is wrong. However, there are two important
medical conditions in which the skin becomes darker - 'acanthosis
nigricans' and 'haemochromatosis'.
Acanthosis
nigricans is the medical term for dark brown/black areas
of skin that have a velvety texture. There are often tags
of skin on or around the affected areas. Acanthosis nigricans
can occur under the arms, in the groins, on the back of
the neck and around the opening of the vagina (vulva). It
is most common in people with dark skin - more than 1 in
10 African Americans and one in 20 Hispanic Americans have
it, but only 1 in 100 white Americans.
Acanthosis
nigricans may be a sign that the body's metabolism is out
of balance. For example, many people who have it are very
overweight, with a tendency to diabetes. It can also be
a sign of hormone problems (such as polycystic
ovary syndrome. In rare cases, it can be a sign of an
internal cancer. So if you think you have acanthosis nigricans
you need to see your doctor for a general check-up, including
a diabetes check.
If
a very overweight person with acanthosis nigricans loses
weight, the dark patches usually fade away. Otherwise, retinoid
creams (as used for acne)
may help.
In
haemochromatosis, the skin over the whole body becomes darker.
In pale-skinned people, it makes the skin look a slate-grey
colour. Haemochromatosis is caused by a disorder of the
metabolism of iron in the body. It can lead to many health
problems (including liver damage), so it needs specialist
treatment.