Acanthosis Nigricans as a Cause of Facial M Elanosis (Clinical Andhistopathological Study)

Background: There are many causes of facial melanosis like melasma , lichen planus actinicas, frictional melanosis , post inflammatory hyperpigmentation but acanthosisnigricans was not well recognized as a cause of facial pigmentation . Objectives: To evaluate all cases of acanthosis nigricans of face, clinically and histopathologically and to study other associated features of acanthosis nigricans. Patients and Methods: Thirty cases of acanthosis nigricans of the face were included in this case descriptive, clinical and histopathological study. This was conducted in Department of Dermatology – Baghdad Teaching Hospital, Baghdad, Iraq during the period from November 2012 to August 2014. It consisted of 29 males and one female their ages ranged from 16-58( 39±4.9) years. History and examination were emphasized to all points related to the disease. Clinical grading of acanthosis nigricans of face was carried out regarding the following points: texture ( thickness of acanthosis and velvety) and color changes. To assess the severity of the acanthosis nigricans of the face Sharquie's scoring system so called Acanthosis Nigricans Severity Index (ANSI) was invented to measure the severity of acanthosis nigricans and to be correlated with other manifestations of the disease. Biopsies was carried out from 2 sites, from the face for each patient and from the neck for 12 patients and processed for histopathological evaluation. Results: All patients presented with facial melanosis as their main problem. Clinical assessment showed all features of acanthosis nigricans including: dark pigmentation, thickening of skin and velvety texture . Associated features of disease like skin tags, seborrhea, planter hyperkeratosis in different severity were noticed. The main other sits that were affected with acanthosis nigricans were neck, axillae and groin. Obesity was noticed in 16( 53.3%)patients while overweight was seen in 10 (33.3%) patients . The third and fourth decades of life were the commonest age groups affected. The males were more affected (96.67%) than females (3.33%). Skin phototype were mainly type III and IV. Sharqie's grading of acanthosis nigricans of the face showed grade II in 8(26.6%) and grade III in 13 (43.3%) while grade IV in 9 (30%) patients. ANCI score was ranged from 4–62 (29.66 ± 17.78). The histopathological examination of acanthosis nigricans of the face showed mainly acanthosis, with or without mild papillomatosis, basal and dermal melanosis. While the histopathological assessment of neck acanthosis nigricans showed similar features but the findings were much more exaggerated and intense. Conclusion: Acanthosis nigricans of the face is an important cause of facial melanosis among males where melanin deposition was detected in basal layer and dermis. The present study showed that clinical and histopathological pictures and the associated findings of acanthosis nigricans of the face were similar to acanthosis nigricans of the body especially neck and axillae. Hence acanthosis nigricans of the face especially early cases might easily mixed up with melasma, frictional melanosis and butterfly lichen planus actinicus.