Thickening of the skin on the forehead: a quiz. Acanthosis nigricans with forehead location

Review of facial acanthosis nigricans: Easy to diagnose and difficult to treat marker of hyperinsulinemia/metabolic syndrome

Facial acanthosis nigricans (FAN) is an increasingly discussed anatomical variation of acanthosis nigricans (AN). Its presentation as brown to black pigmentation with ill-defined blurred margins with varying degree of textural changes commonly over forehead, temporal, and malar regions of the face predominantly in dark-skinned individuals with a male predilection can be confused with other common facial melanoses. Its pathogenesis, clinical features, and management are in many ways similar to in the commonly described areas like neck and major flexural areas. Understanding of FAN has gained momentum in the past decade with studies highlighting its association with various metabolic abnormalities particularly insulin resistance and obesity. It is now being considered to be a cutaneous marker of metabolic syndrome. While there is uniformity in its clinical description, there appears to be scope for further in depth biochemical and histopathological studies to link the pigmentation, altered texture and microscopic changes in individuals presenting with FAN and hyperinsulinemia with or without other features of metabolic syndrome. It awaits a consensus on grading its severity and correlating it with histological features as patients often hesitate to be subjected to a biopsy of the face. This is a review of current literature pertaining to FAN. Newer clinical, dermoscopic, histopathological, and biochemical insights will help to understand this relatively new entity.

Acanthosis Nigricans: An Updated Review

BACKGROUND

Early recognition of acanthosis nigricans is important because acanthosis nigricans can be a cutaneous manifestation of a variety of systemic disorders and, rarely, as a sign of internal malignancy.

OBJECTIVE

The purpose of this article is to familiarize pediatricians with the clinical manifestations, evaluation, diagnosis, and management of acanthosis nigricans.

METHODS

A search was conducted in November 2021in PubMed Clinical Queries using the key term "acanthosis nigricans". The search strategy included all clinical trials, observational studies, and reviews published within the past 10 years. Only papers published in the English literature were included in this review. The information retrieved from the above search was used in the compilation of the present article.

RESULTS

Acanthosis nigricans is characterized by symmetric, hyperpigmented, and velvety plaques with ill-defined borders, typically involving intertriginous areas. Obesity is the most common cause of acanthosis nigricans which is increasingly observed in obese children and adolescents and can serve as a cutaneous marker of insulin resistance. Early recognition of acanthosis nigricans is important because acanthosis nigricans can also be a cutaneous manifestation of a variety of systemic disorders and, rarely, as a sign of internal malignancy. This may consist of weight reduction, discontinuation of causative drugs, treatment of underlying endocrinopathy, or treatment of an underlying malignancy. For patients with isolated acanthosis nigricans and for those whose underlying cause is not amenable to treatment, treatment of the lesion may be considered for cosmetic reasons. Topical retinoids, vitamin D analogs, chemical peels, and other keratolytics are often used for the treatment of localized lesions. Seldom, systemic therapy such as oral retinoids may be considered for extensive or generalized acanthosis nigricans and acanthosis nigricans unresponsive to topical therapy. Other uncommon treatment modalities include dermabrasion, laser therapy, and surgical removal.

CONCLUSION

Although acanthosis nigricans is treatable, a complete cure is difficult to achieve. The underlying cause should be treated, if possible, to resolve and prevent the recurrence of acanthosis nigricans. The diagnosis is mainly clinical, based on the characteristic appearance (symmetrically distributed, hyperpigmented, velvety, papillomatous, hyperkeratotic plaques with ill-defined borders) and the typical sites (intertriginous areas, flexural area, and skin folds) of the lesions. The diagnosis might be difficult for lesions that have atypical morphology or are in an unusual location. Clinicians should be familiar with the clinical signs, evaluation, diagnosis, and therapy of acanthosis nigricans because of the link between it and underlying diseases.

Acanthosis nigricans in obese adolescents: prevalence, impact, and management challenges

Obesity in adolescence is a public health priority because it usually tracks into adulthood, resulting in enormous medical and social costs. This underscores the importance of early identification and intervention. Acanthosis nigricans (AN) was once considered a rare paraneoplastic dermatosis, but is now frequently observed in obese adolescents. Current understanding suggests that it is associated with insulin resistance and has a unique role in secondary prevention. The purpose of this narrative review is to provide a comprehensive overview of AN in obese adolescents, covering its history, current knowledge on the condition, its clinical significance, management challenges, and the direction of future research.