Skin cancers of the face in an African Black population

The localization of skin cancers on the face is a major concern for the dermatologist. Indeed, because of its intense solar exposure, about 80% of skin cancers sit selectively in this region, although it only represents 9% of the body surface area [1,2]. On the other hand, the management of cancers in this highly visible region requires a compromise between clinical and aesthetic results [3]. Despite their frequency, very few studies have focused on malignant tumors on the face throughout the world and, to our knowledge, none in subSaharan Africa [1,4,5]. The purpose of this study was, therefore, to report the frequency and -clinico-anatomical features of skin cancers on the face in a black African population.


Introduction
The localization of skin cancers on the face is a major concern for the dermatologist. Indeed, because of its intense solar exposure, about 80% of skin cancers sit selectively in this region, although it only represents 9% of the body surface area [1,2]. On the other hand, the management of cancers in this highly visible region requires a compromise between clinical and aesthetic results [3]. Despite their frequency, very few studies have focused on malignant tumors on the face throughout the world and, to our knowledge, none in sub-Saharan Africa [1,4,5]. The purpose of this study was, therefore, to report the frequency and -clinico-anatomical features of skin cancers on the face in a black African population. patient with facial skin cancer was 50 years [ranged from 4 to 85 years] and the majority (56.5%) were over 50 years of age.
The sex ratio (M/F) was 1.19.

Summary
Introduction: The aim of this study was to evaluate the frequency and clinico-anatomical features of facial skin cancers in an African Black population.

Patients and methods:
It was a retrospective, descriptive study of all cases of skin cancer localized on the face, seen in our department over a 21-year period.

Conclusion:
In sub-Saharan Africa, the localization of skin cancer on the face is rare, dominated by SCC, which often occurs on precancerous skin lesions, especially actinic cheilitis and genodermatosis. The BCC and melanoma are exceptionally rare on the face. DOI: http://doi.org/10.17352/2455-1759.000056 leukoplakia of the oral mucosa (due to prosthesis and mucosal lichen planus) in 2 cases and hydroquinone-induced exogenous ochronosis in one case (Figures 2,3).
A facial localization of a PCL was noted in 9 patients (%). They consist of NK/T-cell lymphoma, nasal type in 4 patients, Anaplastic CD30 + lymphoma in 3 cases and of mycosis fungoide in 2 cases (Figure 4).
We observed seven cases (14.6%) of BCC on the face ( Figure  5). It was a nodular BCC in 5 cases and ulcerated BCC in 2 cases. The BCC was located on the nose and cheek in 3 cases each and on the lower eyelid in one case.
Two cases of DFS on the cheek were found, corresponding to 9.1% of the 22 cases of DFS observed during the same period. A case of eccrine adenocarcinoma, rhabdomyosarcoma, melanoma and a case of primary angiosarcoma were also observed ( Figure 6).

Discussion
Studies on facial skin cancers are rare and date back to a long time [1,2,4]. Despite the limitations of our study, this is, to our knowledge, the fi rst study on the characteristics of skin cancers on the face in a black population.
In contrast to the white population in which about 40% of skin cancers occur on the face, the localization in this region seems very rare in the Black African population [6][7][8]       skin cancers are not often related to solar exposure, but rather to precancerous skin lesions (ulcers, burn scars) that sit rather selectively on the legs [7]. The SCC represents by far the most common skin cancer on black skin [8]. In our cohort of patients, there was a clear predominance of the SCC, which, alone, accounted for more than half (54.2%) of skin cancers in this region. Through this study, it can be said that in the black subject, the SCC seems to be the most frequent regardless of the topography. In contrast, in the white population, facial skin cancers are widely dominated by BCC [9]. The lower limb is the preferential localization of the SCC in Black African population [7]. Thus, in our study, facial involvement accounted for only 21.3% of cases. On the contrary, in fair-skinned subjects, the SCC predominates at the cephalic extremity [2,9]. On the other hand, in white population, the SCC of the face has a predilection for the nose and the ears, generally occurring on actinic keratosis lesions favored by solar exposure [1,6]. In our study, the SCC was mostly found on the lower lip (38.5%) and the cheeks (34.6%), promoted by the topography of the precancerous skin lesions, especially genodermatoses as well as actinic cheilitis, which is particularly frequent in black Africans.
\Moreover, the occurrence of a SCC on lesions induced by skin bleaching, as observed in one of our patients, has been rarely reported in the medical literature [10].
Apart from the SCC, PCL was the most common facial cancer in our study (18.75%). Unlike in the white polulation, the PCL on the face, were dominated, in our cohort, by T-cell lymphoproliferations (mycosis fungoide and anaplastic CD30+ lymphoma), as well as NK/T-cell lymphoma, nasal type. This latter is rarely reported in Africa, despite the prevalence and precocity of the Epstein-Bar virus infection, unlike in Asia and South America [11].
In our study, only 7 cases of BCC (14.6%) were located on the face. This is merely related to the rarity of this tumor on black skin, in which its prevalence is estimated at 1 / 100,000 inhabitants [8,12,13].
It is the same with melanoma in black skin, because of its preferential localization on the feet. The occurrence of DFS on the face, as noted in our 2 patients is exceptionally rare [14]. The same is true for rhabdomyosarcoma. Contrariwise, the localization of angiosarcoma and adnexal tumors on the face is usual [15].
In addition, some skin cancers frequent on the face, such as Merkel cell carcinoma, have not been found in our study because of their rarity in the black population.

Conclusion
In the black African population, skin cancers rarely occur on the face. In this region, they are also still dominated by squamous cell carcinoma, which is frequently found on the lower lip and cheeks and favored by precancerous skin lesions, notably actinic cheilitis and genodermatosis. The SCC was followed by cutaneous lymphomas mainly T and NK/T-cell nasal type, while BCC and melanoma are exceptionally rare on the face of black African skin.