Vulvar Acanthosis Nigricanscolon; A Marker for Insulin Resistance in Hirsute Women

摘要

Acanthosis nigricans (AN) presents as a thickened pigmented velvety skin lesion. Lesions may involve practically any area of the body. The predominant site is in the crural folds. A syndrome which consists of hyperandrogenism, insulin resistance, and AN has been described. This cross-sectional, observational study was designed to determine the frequency of AN in a group of hirsute, hyperandrogenic women, and to determine the body site most frequently affected.The study was conducted in a university teaching hospital. Women referred with the primary complaint of hirsutism were enrolled in the study. Fifteen normal, nonobese women were used as controls. Obesity was defined as greater than 120 per cent of ideal body weight. The presence of a demarcated, pigmented lesion on the vulva with variable degrees of velveted change found in a butterfly distribution was considered positive for AN. All patients had hyperandrogenism documented by elevation of 1 or more of the following hormonescolon; unbound testosterone, androstenedione, and dehydroepiandrosterone sulfate. Insulin resistance was assessed by measuring fasting glucose, fasting insulin, and nadir glucose after a 0.1-U/kg I.V. insulin bolus in both obese and nonobese hirsute hyperandrogenic women.Twenty-four of the 43 women were found to have AN. Although lesions were detected at multiple body sites, all patients had vulvar lesions (Table 1). Lesions were also noted frequently on the neck and in the axilla. None of the nonobese, hirsute hyperandrogenic patients were found to have this lesion (Table 2). Among 31 hirsute, hyperandrogenic, obese patients, 24 were found to have AN. Obese hirsute women with AN had higher fasting insulin, higher fasting glucose concentrations, and higher glucose nadir values after a bolus of insulin. This indicates a greater degree of insulin resistance in these patients.The authors conclude that AN and insulin resistance are found frequently in obese, hirsute, hyperandrogenic women. A close inspection of the vulva will usually result in detection of this typical lesion. Finding an AN lesion on the vulva should alert the clinician to the probability of significant metabolic alteration.