Acanthosis nigricans in a Japanese boy with hypochondroplasia due to a K650T mutation in FGFR3

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, hypochondroplasia, and FGFR3 mutations: Findings with five new patients, and a review of the literature

Early development of extensive acanthosis nigricans (AN) is a key feature in some patients who have hypochondroplasia (HCH) in association with FGFR3 mutations. We here report regarding five new patients with HCH who exhibited AN, and we compare their characteristics to the eight patients previously described in the literature. In these patients, the AN lesions began in childhood, and they were extensive. These lesions were located on the torso, the abdomen, and the face, in addition to the typical skin fold sites. Other skin lesions were frequently reported: café-au-lait macules, melanocytic nevi, lentigines, and seborrheic keratosis. The Lys650Thr mutation was the predominant reported mutation of FGFR3.

Acanthosis nigricans in a Chinese girl with FGFR3 K650 T mutation: a case report and literature review

Background

Acanthosis nigricans (AN) is a clinical manifestation featured by velvety brown plaques in skin folds that occurs in some hereditary and syndromic disorders. Fibroblast growth factor receptor 3 (FGFR3) mutations have been identified as one of the genetic causes of inherited AN.

Case presentation

A 17-year-old Chinese female had presented generalized acanthosis nigricans since she was 4 years old. She yielded no family history of short stature or AN. Apart from a short stature, no skeletal defects, neurological defects or other abnormalities were found. To identify the aetiology of the clinically diagnosed AN, we screened the proband for genetic mutations using whole exome sequencing. A heterozygous mutation (c.1949A > C, p.Lys650Thr) in FGFR3 was found in the proband. To date, 26 cases of AN harbouring this specific gene mutation have been reported in the literature, and only one child carried a de novo mutation instead of inheriting the specific mutation from their parents. The present case is the first-reported Chinese patient with isolated AN with a de novo K650 T mutation in FGFR3.

Conclusions

We reported a new case of AN caused by a heterozygous mutation (c.1949A > C, p.K650 T) in FGFR3, and review the past reports of AN with the same gene mutation. Sequencing of the FGFR3 gene is a feasible approach to identify the aetiology of AN, especially for early onset extensive AN.

Electronic supplementary material

The online version of this article (10.1186/s12881-019-0748-4) contains supplementary material, which is available to authorized users.

Electronic supplementary material

The online version of this article (10.1186/s12881-019-0748-4) contains supplementary material, which is available to authorized users.

Achondroplasia: a comprehensive clinical review

Achondroplasia is the most common of the skeletal dysplasias that result in marked short stature (dwarfism). Although its clinical and radiologic phenotype has been described for more than 50 years, there is still a great deal to be learned about the medical issues that arise secondary to this diagnosis, the manner in which these are best diagnosed and addressed, and whether preventive strategies can ameliorate the problems that can compromise the health and well being of affected individuals. This review provides both an updated discussion of the care needs of those with achondroplasia and an exploration of the limits of evidence that is available regarding care recommendations, controversies that are currently present, and the many areas of ignorance that remain.

Acanthosis nigricans in achondroplasia

Acanthosis nigricans (AN) in those with achondroplasia has been reported occasionally in the literature previously. Other disorders arising from constitutive activation of FGFR3 also manifest AN at various frequencies. We assessed the prevalence of AN in a sequential series of 477 individuals with achondroplasia. Using a REDCap database, we collected and analyzed what other features or medical issues may co-occur with AN in those with achondroplasia. AN arises in approximately 10% of individuals with achondroplasia. It usually first appears in preadolescence or adolescence, is more likely in the non-White population and in those who are obese. It is not severe and generally will need no treatment. It is not associated with any evident risk for neither hyperinsulinemic states nor malignancy, and therefore, no special investigations are warranted when it is recognized. Thus, clinicians should not be surprised or concerned upon discovering this finding in those with achondroplasia. In addition, the mechanisms and genetic causes of AN are detailed.