The prevalence of melanoma or skin cancer is seen
mostly in people who have white skin. Melanoma occurs
less frequently among blacks, Asians, Central and
South American populations. The reason for this can
be attributed to the fact that the latter group is
better protected against the environment due to their
skin pigmentation and possibly their exposure to the
sun is different and done wisely.
In the United States, for every one black Afro American
person with melanoma there are 17 Caucasians suffering
from this disease. However, it must always be kept
in mind that people with pigmented skin can develop
melanoma and are also at risk though the incidence
is lower. Just as in white populations, dermatoscopy
seems to be the best method in detecting melanomas
in non-white populations as well.
The Risk areas
For people with dark skin, melanomas are found to
occur in the relatively non-pigmented areas of the
skin like the palms of the hands, soles of feet and
under the nails. To dermatologists these types of
melanomas are called the acral lentiginous type or
Delay in Diagnosis
Melanoma, though low in incidence among non-whites,
have poorer prognoses compared to white skinned populations
due to the increased chance of late diagnosis. This
problem can be attributed to the fact that in non
white populations, pigmented skin lesions are rarely
noticed and are difficult to detect by clinical examination.
This results in delayed initiation of treatment compared
to whites where these lesions are more easily noticeable.
So reduced visibility of melanocytic lesions leads
to delay in seeking medical help. This is further
compounded when examination by physicians using the
naked eye results in misdiagnosis or when the examination
is not conducted properly. It has been shown that
when diagnosed in the correct manner, at an early
stage, prognosis of melanoma in non-white populations
is comparable to that in case of white populations.
Using a dermatoscope to examine dark skin for melanomas
could help improve the chances of correct diagnosis
and earlier treatment intervention
Dermatoscopy as essential in dark skin as in white
For non whites, poor prognosis due to delay in diagnosis
makes it all the more vital that this population is
made aware of this fact. In addition, dermatologists
need to be skilled in differentiating melanocytic
lesions from physiological pigmentation and should
be well versed in the use of superior detection instruments.
While in whites, naked eye examination alone is insufficient
in detecting problem areas, in dark skinned individuals
this becomes a double jeopardy.
It is therefore imperative that physical examination
is more effectively done by dermatologists for early
detection and consequent successful immediate therapy.
In this way the lower incidence of melanoma in non-whites
should not stop dermatologists from making early diagnosis
and accurately classifying pigmented lesions.
In the last decade, the use of Dermatoscopy in clinical
dermatological practice has played an important role
in improving diagnostic accuracy. Lesions appearing
suspicious by eye examination can be grouped correctly,
thereby reducing misdiagnosis by clinical examination
resulting in the incidence of unnecessary excisions
Proven Superiority of Dermatoscopy Over Other Methods
In whites, it has been proved that dermatoscopy is
able to improve diagnostic results in examination
of pigmented lesions and this has encouraged dermatologists
to progressively adopt this technique over clinical
examination based solely on the naked eye examination
method. Studies have also confirmed that the use of
dermatoscopy in the detection of pigmented lesions
in non-whites and blacks can lead to early and accurate
diagnosis of melanoma.
It has been confirmed through experiments that there
is a 97% success rate in detection of lesions accurately
in people with dark skin with the use of Dermatoscopy.
There is a high level of interobserver agreement for
the dermoscopic variables like pigmented lesions,
streaks, globules, blue-whitish veils, and milia like
Clark nevi were easily diagnosed by the use of dermatoscopy
in this group by a network of pigment and presence
of globules. Benign melanocytic lesions were also
detected as were sebhorric keratoses, which were characterized
by presence of milia like cysts. Blue naevi revealed
bluish pigmentation. The melanomas in dark skinned
people were confirmed by the presence of bluish white
veils, irregular globules and streaks at the edges
in the same manner that it is confirmed in cases of
melanoma in white skinned people.
So, dark skin does not impede the identification
of any dermoscopic feature. Naked eye examination
on the other hand poses a problem of misdiagnosis.
However, in some dark skinned people, a stronger source
of light is used with the dermatoscope, as dark skin
tends to absorb a large amount of light rays. The
newer dermoscopes improve vision due to excellent
light emitting diode illumination.
Just as in case of the caucasian population, demoscopy
is equally effective and superior as a method of melanoma
detection in the dark skin populations as well. It
plays a more vital role in this group as only by this
method is it possible to detect melanocytic lesions
accurately and timely enabling early therapy, reduction
in the number of unnecessary excisions, reduction
in scarring, and lowering social costs.