Introduction

‘A dermatological diagnosis is an art, not a science.’
This point of view is especially true, when looking upon dermatology and concerning the aspect of great variance in skin type. Understanding dermatological disease in pigmented races demands a number of insights from the clinician, which are necessary to be able to apply the classical classification of dermatological disease. For example; to be able to distinguish normal and abnormal pigmentation of the skin and insight in presence/absence of the symptom colour.
Besides, certain types of reactions occur more often in the dark skin, compared to the white of yellow skin. In general the dark skin tends more often towards the following pathology:

- pigment shifts
- follicular and papulous disease
- keloid lesions
- annular arranged dermatosis

It goes without saying that for example granulomatous diseases result in similar characteristics in the white as in the pigmented skin, except for accompanying pigment alterations in the epidermis and dermis. One should be aware of gradual differences in the histological aspect, which may occur, compared to the white skin. These may develop due to a stronger tendency towards fibroblastic granulomatous reaction patterns, which are commonly seen in the pigmented skin. This could also explain the relatively high incidence of papulous and annular manifestations of dermatosis.

The pigmented skin has a number of normal (physiological) variances, which do not occur in the non-pigmented skin. These include Futcher’s or Voight’s lines, linea alba, Mongolian spots, pigmentation of the nails, pigmentation of tongue and oral mucosa, hyperpigmentation of the maculae of the sole of the foot, leukoderma of the oral mucosa, pearly penile papules and keratosis of the palm of the hand and the sole of the foot. It is very important for doctors, especially dermatologists to be able to recognize these phenomena in the pigmented skin, to avoid confusion with pathological symptoms and subsequent unnecessary medical treatment. For example leukoderma, one of the non-pigmented variants, which often occurs on the Negroid skin, is a benign white/grey, non-keratotic lesion of the oral mucosa. This should be distinguished from pathological changes, such as leukoplakia, lichen planus and oral candidiasis, which naturally also occur in the Negroid skin.

Another aspect, related to the increasing migration from in particular developing countries, is the issue of foreign diseases. These are often infectious diseases which are less known in this region and which obviously need to be recognized in time. A known example is leprosy, an infectious disease which has a varied clinical presentation. Recognizing the efflorescences in the pigmented skin, which determine the different manifestations of leprosy, is a prerequisite. In addition, parasites may be encountered which cause syndromes like the cutaneous larva migrans, schistosomiasis and filariasis.

In conclusion: also in paediatric dermatology the skin displays it’s own character. Syndromes that occur more frequently are transient neonatal pustular melanosis, infantile acropustulosis, tinea capitis, pomade acne, traction alopecia and proximal trichorrhesis nodosa. A number of these are related to customs in certain Negroid populations (traction alopecia), others are probably caused by the special structure of the skin.

In the pigmented skin, annular lesions often occur in the face. For example secondary syphilis, especially in the circumference of the mouth, and sarcoidosis, which never occur in the Caucasian skin.

Seborrheic eczema lesions, which are more frequently seen in the Negroid skin than in the Caucasian skin, can also be found as annular papulosquamous lesions in the face.