Abstract

Acanthosis nigricans is a velvety, darkening of the skin that usually occurs in intertriginous areas.  This hyperpigmentation has poorly defined borders, usually occurs in skin fold areas, such as the back of the neck, axilla, and groin, and may include thickening of the skin. Acanthosis nigricans is most commonly associated with diabetes and insulin resistance

Acanthosis nigricans has a strong association with obesity and insulin resistance. Assessment involves a thorough physical exam to differentiate from other dermatosis, as well as full workup for insulin resistance. Early diagnosis in the urgent care setting, and treatment, will improve the appearance of acanthosis nigricans, but also the patient’s overall morbidity.

Introduction

A38-year-old male presented for a circumferential hyperpigmented rash around the neck that began several months ago. Family history was significant for diabetes in family.

Physical inspection of the neck area revealed circumferential velvety, papular, hyperpigmented rash and skin tags. Areas of rash did not blanch with pressure palpation and were not associated with pruritus or discomfort. The rest of physical inspection was within normal limits.

Case

Patients neck rash was determined to be acanthosis nigricans secondary to insulin resistance. Physical exam suggested the neck rash being acanthosis nigricans due to its chronic nature, as well as the velvety, unblanching characteristics with no pruritus. Patient was also worked up for insulin resistance with fasting serum glucose and hemoglobin A1C.

As acanthosis nigricans is associated with diabetes, He was on oral metformin extended-release 750 mg once daily and counseled on lifestyle changes and exercise. 

Discussion

Acanthosis nigricans is a benign, asymptomatic dermatosis characterized by velvety, hyperpigmented plaques most commonly found on surfaces of the neck and axilla. A thorough physical exam will differentiate acanthosis nigricans from its dermatosis counterparts, mainly through physical appearance and the absence of pruritis in acanthosis nigricans.

Acanthosis nigricans is closely associated with obesity and insulin resistance. This case study demonstrates the importance of a systemic approach to treating dermatosis in an acute setting. In patients with no history of insulin resistance but who are obese and have acanthosis nigricans, a full workup for diabetes mellitus should be performed. If a diagnosis of diabetes is reached, patients should be counseled on weight loss and started on agents that improve insulin sensitivity.

Treatment

Treatment of underlying malignancy is the preferred therapy for those with malignancy-associated acanthosis nigricans. The patient was put on topical treatment. Often times 0.1% tretinoin is successful at lightening the hyperpigmented lesions. 

For continuous use, emollient cream such as salicylic acid have been described as the best options.

Conclusion

In the case reported here, the patient was treated with tretinoin, showing partial improvement of skin lesions. 

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