Fa­cial hy­per­pig­men­ta­tion or dark­en­ing of the skin of the face is the cause for much dis­tress and is a com­mon com­plaint in the der­ma­tol­o­gist's of­fice. The colour of an in­di­vid­ual's skin is pre­de­ter­mined by the amount and dis­tri­b­u­tion of melanin (a brown-black nat­ur­al pig­ment which pro­tects us from sun­light) and the man­ner in which it ab­sorbs, re­flects and back-scat­ters light. The same con­cen­tra­tion of pig­ment cells (lo­cat­ed in the up­per lay­er of skin called the epi­der­mis) is present in peo­ple of all races who have nor­mal skin. How­ev­er, some races have larg­er melanosomes (pig­ment pack­ages), giv­ing their skin a dark­er colour. Hy­per­pig­men­ta­tion may in­volve the en­tire face or be lo­calised to ar­eas af­fect­ed by rash­es. It may be the sign of a be­nign or rel­a­tive­ly-eas­i­ly-treat­ed con­di­tion, or it may in­di­cate the pres­ence of a life-threat­en­ing con­di­tion such as melanoma (skin can­cer).

Le­sions from chron­ic sun dam­age

The nor­mal re­sponse to sun ex­po­sure is an in­crease in melanin pro­duc­tion, which caus­es uni­form tan­ning in most per­sons. Fur­ther dark­en­ing can be pre­vent­ed by the use of sun­screen lo­tions or creams ap­plied about half an hour be­fore sun­light ex­po­sure. Sun­screens with a sun­light pro­tec­tion fac­tor (SPF) of at least 30 are rec­om­mend­ed for peo­ple who are ex­posed to ex­treme sun­light. Pro­tec­tive cloth­ing like hats and long sleeves are im­por­tant. Some peo­ple de­vel­op freck­les when they are ex­posed to sun­light. Freck­les are small (usu­al­ly less than 3 mm in di­am­e­ter), red or light-to-dark-brown flat spots that ap­pear on sun-ex­posed ar­eas of the body. Moles, in­clud­ing those that are present from birth, may al­so be flat and dark but if they be­come larg­er than sev­er­al mil­lime­tres or dis­play ab­nor­mal col­oration or be­come raised or ir­reg­u­lar in out­line, they may re­quire test­ing (biop­sy) or sur­gi­cal re­moval be­cause of pos­si­ble skin can­cer called melanoma.

Hy­per­pig­men­ta­tion from skin rash­es

When in­flam­ma­tion takes place in the skin from rash­es such as ac­ne, eczema or a less com­mon con­di­tion called lichen planus, pig­ment cells may be dam­aged. This caus­es the cells to re­lease their pig­ment in­to the deep­er lay­ers of the skin. Any in­jury to the skin such as scratch­ing or squeez­ing of pim­ples fur­ther in­creas­es the like­li­hood of pig­men­ta­tion. The dark skin usu­al­ly clears with treat­ment of the con­di­tion and the use of sun­light pro­tec­tion. Some­times it may be nec­es­sary to use bleach­ing creams or chem­i­cal peels.

Pho­to­tox­ic re­ac­tions

Hy­per­pig­men­ta­tion can be caused by pho­to­tox­ic re­ac­tions from the use of oral or top­i­cal med­ica­tions or from con­tact with cer­tain plants or foods in con­junc­tion with sun ex­po­sure (phy­topho­to­der­mati­tis).

These can be enough to cause blis­ter­ing in sun ex­posed sites. The in­flam­ma­tion even­tu­al­ly set­tles lead­ing to what is termed post in­flam­ma­to­ry hy­per­pig­men­ta­tion. Some med­ica­tions re­sult in hy­per­pig­men­ta­tion, with­out sun ex­po­sure, in a dif­fuse pat­tern. Ex­am­ples of plants and foods that may be as­so­ci­at­ed with phy­topho­to­der­mati­tis in­clude lemons, limes, cel­ery, dill, and car­rot juice. erg­amot-a com­mon in­gre­di­ent found in per­fumes and cit­rus-scent­ed prod­ucts such as the lo­cal­ly-pop­u­lar Li­ma­col, can lead to face and neck hy­per­pig­men­ta­tion.

Melas­ma (chloas­ma, "the mask of preg­nan­cy")

Preg­nan­cy or the use of hor­mones (eg oral con­tra­cep­tive pills) can cause melas­ma, a lo­calised fa­cial hy­per­pig­men­ta­tion. While melas­ma may regress af­ter preg­nan­cy, it may in­crease with each sub­se­quent preg­nan­cy. Al­though main­ly women get melas­ma, it is oc­ca­sion­al­ly seen in men. Pa­tients who de­sire treat­ment may at­tempt a tri­al of bleach­ing agents af­ter patch test­ing else­where on the body. Bleach­ing agents can, how­ev­er, cause ir­ri­ta­tion and fur­ther in­crease in pig­men­ta­tion. Tretinoin cream and hy­dro­quinone-a bleach­ing agent, have been the main­stays of top­i­cal treat­ment. Com­bin­ing both can im­prove the re­sult. Aze­la­ic acid, ko­jic acid, and al­pha-hy­droxy acids al­so have been use­ful in the treat­ment of melas­ma. Strict avoid­ance of sun ex­po­sure is im­por­tant to pre­vent re­cur­rence. Laser ther­a­py may be used for some cas­es of melas­ma, but the skilled use of lasers by pro­fes­sion­als is of ut­most im­por­tance to pre­vent com­pli­ca­tions.

Acan­tho­sis Ni­gri­cans

Acan­tho­sis ni­gri­cans is thick­ened, dark skin that can af­fect oth­er­wise healthy peo­ple or it can be re­lat­ed to un­der­ly­ing med­ical prob­lems. Some cas­es are ge­net­i­cal­ly in­her­it­ed. Obe­si­ty and weight gain dur­ing preg­nan­cy can lead to acan­tho­sis ni­gri­cans, as can some en­docrine dis­or­ders, most com­mon­ly di­a­betes. It usu­al­ly af­fects the neck, un­der arms, in­ner thighs, back of the hands and less com­mon­ly the sides of the face. Some drugs, par­tic­u­lar­ly hor­mones such as hu­man growth hor­mone or oral con­tra­cep­tives ("the pill"), can al­so cause acan­tho­sis ni­gri­cans. If you have ab­nor­mal dark­en­ing of the fa­cial skin, it may be nec­es­sary to con­sult your doc­tor to de­ter­mine the cause and pos­si­ble treat­ment.

Sub­mit­ted by The Trinidad and To­ba­go Der­ma­to­log­i­cal So­ci­ety