Lesions which are darker than normal skin can be brown, black, or sometimes blue-gray.

The distribution and arrangement of lesions are important semiological elements to be specified, as well as the circumscribed or diffuse nature of the pigmentary disorder. A mucous involvement must also be investigated. Certain topographies are noteworthy.

Circumscribed disorders correspond to macules or pigmented patches that are clearly individualized, whereas diffuse lesions are poorly defined and generally widespread. Pigmentary disorders are often diffuse; they usually first appear and predominate in sun-exposed areas. When a pigmentary disorder is diffuse, it can sometimes be difficult to determine whether the pathological component is the one which is too pigmented or, on the contrary, the one which is lighter. History taking, comparison to naturally less pigmented skin (e.g., inner arms), and comparison to other members of the family can thus be decisive.

Sometimes hyper- and hypopigmented lesions may ­coexist in what is known as dyschromatosis.

The color of the lesions gives an indication of the type of pigmentary disorder:

In general, the cutaneo-conjunctival yellow coloration of icterus (jaundices), the orange-yellow color which spares the conjunctivae in carotenemias, as well as the ochre, light brown, or reddish brown coloration due to hemosiderin deposits, readily suggests the diagnosis.

The distribution, arrangement, and topography of the lesions provide an important help to diagnosis (Tables 17.1 and 17.2).