Acanthosis nigricans as a composite marker of cardiometabolic risk and its complex association with obesity and insulin resistance in Mexican American children

AIM

Acanthosis nigricans (AN) is a strong correlate of obesity and is considered a marker of insulin resistance (IR). AN is associated with various other cardiometabolic risk factors (CMRFs). However, the direct causal relationship of IR with AN in obesity has been debated. Therefore, we aimed to examine the complex causal relationships among the troika of AN, obesity, and IR in Mexican Americans (MAs).

METHODS

We used data from 670 non-diabetic MA children, aged 6-17 years (49% girls). AN (prevalence 33%) severity scores (range 0-5) were used as a quasi-quantitative trait (AN-q) for analysis. We used the program SOLAR for determining phenotypic, genetic, and environmental correlations between AN-q and CMRFs (e.g., BMI, HOMA-IR, lipids, blood pressure, hs-C-reactive protein (CRP), and Harvard physical fitness score (PFS)). The genetic and environmental correlations were subsequently used in mediation analysis (AMOS program). Model comparisons were made using goodness-of-fit indexes.

RESULTS

Heritability of AN-q was 0.75 (p<0.0001). It was positively/significantly (p<0.05) correlated with traits such as BMI, HOMA-IR, and CRP, and negatively with HDL-C and PFS. Of the models tested, indirect mediation analysis of BMI→HOMA-IR→AN-q yielded lower goodness-of-fit than a partial mediation model where BMI explained the relationship with both HOMA-IR and AN-q simultaneously. Using complex models, BMI was associated with AN-q and IR mediating most of the CMRFs; but no relationship between IR and AN-q.

CONCLUSION

Our study suggests that obesity explains the association of IR with AN, but no causal relationship between IR and AN in Mexican American children.

Falling short: When testing is mandated and follow-up is not

In 1999, the Texas Legislature mandated acanthosis nigricans (AN) screening in primary schools in designated regions of the state through the passage of House Bill 1860 to identify children at risk for diabetes by identifying the skin condition AN. AN is related to insulin resistance, and, thus, is associated with type 2 diabetes (diabetes mellitus type 2 [DMT2]), a growing concern among school-aged children. Since 1999, millions of children have been screened and hundreds of thousands have been screened positive. No data are available about the effectiveness of the program in identifying DMT2 among the school-aged population because no follow-up is mandated. The current practice is to send a letter to the parents of the child who screens positive, advising the parents to take the child to a health care provider for further assessment. Hence, children within the state may have diabetes or are developing diabetes but have yet to be diagnosed. In light of the presence of a law mandating AN screening, mandating a follow-up to identify those who have diabetes or are developing the condition of diabetes can provide early intervention and decrease costs of care. It is not known why the follow-up of those who screen positive was not included in the initial legislation. It may have been due to the cost of the necessary blood tests that are used to assess an individual for diabetes. Related to this is the reality that blood tests are invasive procedures, whereas screening for a skin disorder is not, thereby possibly explaining the omission of mandated follow-up from the legislation .

Evaluating health risk using a continuous metabolic syndrome score in obese children

BACKGROUND

The metabolic syndrome (MS) in pediatrics is controversial. Rather than a dichotomous scale, a continuous metabolic syndrome score (cMets) has been proposed to evaluate MS. The aim of this study was to evaluate the utility of a cMets score among an ethnically diverse cohort of children with acanthosis nigricans (AN).

METHODS

A retrospective chart review was used to extract clinical and laboratory information on a cohort of obese children. Criteria for MS components and the cMets score were established using published guidelines. Multiple linear regression evaluated the effect of AN status on MS and cMets. Fisher's exact test compared the race differential on the presence or absence of MS component disorders.

RESULTS

MS diagnosis was non-significant when considering AN status (p=0.554) and ethnicity (p=0.431). Evaluation of the frequency of component disorders, revealed that Caucasians had significantly higher levels of abnormal triglycerides (TG) (35.1 vs. 10.3%; p<0.001), whereas African Americans had significantly higher homeostatic model assessment of insulin resistance (HOMA-IR) scores (51.3% vs. 22.3%; p<0.001). cMets was sensitive to identifying metabolic risk among Caucasians with AN, only (p=0.029).

CONCLUSIONS

This study found differences in health risk among an obese, ethnically diverse sample of children. cMets is a more sensitive marker of metabolic change compared with MS, especially when AN status and race are considered. cMets may pose an opportunity for the clinician to evaluate the interaction of health risks on the health status of obese children.

Skin findings associated with obesity

We are facing an obesity epidemic in adolescents in the United States. Thus, practitioners will need to become familiar with cutaneous findings associated with obesity in order to diagnose and treat them properly. This article addresses some of the cutaneous findings associated with obesity.

Pigmented and thickened axillary folds

Andrew, 45 years of age, presents with a 12 month history of dark, thickened skin in both axillae. He is concerned about the appearance and would like to know how to treat it. He is moderately obese, with a body mass index (BMI)of 31.2 kg (BMI = weight [kg] + height(2) [m(2)]) but is otherwise well and on no medication. There is no family history of any similar skin disorder.

Obesity and the skin: Skin physiology and skin manifestations of obesity

Obesity is widely recognized as an epidemic in the Western world; however, the impact of obesity on the skin has received minimal attention. The purpose of this article is to highlight the association between obesity and dermatologic conditions. We review the impact of obesity on the skin, including skin physiology, skin manifestations of obesity, and dermatologic diseases aggravated by obesity. Obesity is responsible for changes in skin barrier function, sebaceous glands and sebum production, sweat glands, lymphatics, collagen structure and function, wound healing, microcirculation and macrocirculation, and subcutaneous fat. Moreover, obesity is implicated in a wide spectrum of dermatologic diseases, including acanthosis nigricans, acrochordons, keratosis pilaris, hyperandrogenism and hirsutism, striae distensae, adiposis dolorosa, and fat redistribution, lymphedema, chronic venous insufficiency, plantar hyperkeratosis, cellulitis, skin infections, hidradenitis suppurativa, psoriasis, insulin resistance syndrome, and tophaceous gout. We review the clinical features, evidence for association with obesity, and management of these various dermatoses and highlight the profound impact of obesity in clinical dermatology.

LEARNING OBJECTIVE

After completing this learning activity, participants should be aware of obesity-associated changes in skin physiology, skin manifestations of obesity, and dermatologic diseases aggravated by obesity, and be able to formulate a pathophysiology-based treatment strategy for obesity-associated dermatoses.

Prediction Models for Insulin Resistance in Girls with Premature Adrenarche

AIM

The purpose of this study was to develop an accurate regression model to predict insulin resistance in girls with premature adrenarche.

METHODS

The insulin sensitivity index was calculated from the frequently sampled intravenous glucose tolerance test with tolbutamide. Thirty-five prepubertal girls (23 Caribbean-Hispanic and 12 African-American; mean age 6.8 years) were studied. The insulin sensitivity index was compared to birth weight, body mass index (BMI), the presence of acanthosis nigricans (AN), insulin-like growth factor 1, insulin-like growth factor binding protein 1, sex hormone binding globulin, lipid profile, and adrenocorticotropic hormone stimulated androgens.

RESULTS

The best prediction models included birth weight, BMI, and AN (model 1: R(2) = 0.78) and BMI, AN, and serum 17-OH pregnenolone (model 2: R(2) = 0.76). When viewed as screening tests, a cutoff value <5.5 (premature adrenarche insulin resistance score) in both equations showed a sensitivity of 100% and a specificity of 85%.

CONCLUSION

Born small for gestational age, premature adrenarche, obesity, AN, and higher serum 17-OH pregnenolone levels may confer negative, but independent, health risks.

Can waist circumference identify children with the metabolic syndrome?

OBJECTIVE

To determine in children the association between waist circumference (WC) and insulin resistance determined by homeostasis modeling (HOMA-IR) and proinsulinemia and components of the metabolic syndrome, including lipid profile and blood pressure (BP).

METHODS

Eighty-four students (40 boys) aged 6 to 13 years and matched for sex and age underwent anthropometric measurements; 40 were obese; 28, overweight; and 16, nonobese. Body mass index (BMI), WC, BP, and Tanner stage were determined. An oral glucose tolerance test, lipid profile, and insulin and proinsulin assays were performed. Children were classified as nonobese (BMI < 85th percentile), overweight (BMI, 85th-94th percentile), and obese (BMI > or = 95th percentile).

RESULTS

There was univariate association (P < .01) between WC and height (r = 0.73), BMI (r = 0.96), Tanner stage (r = 0.67), age (r = 0.56), systolic BP (r = 0.64), diastolic BP (r = 0.61), high-density lipoprotein cholesterol level (r = 0.45), triglyceride level (r = 0.28), proinsulin level (r = 0.59), and HOMA-IR (r = 0.59). Multiple linear regression analysis using HOMA-IR as the dependent variable showed that WC (beta coefficient = 0.050 [95% confidence interval, 0.028 to 0.073]; P = .001) and systolic BP (beta coefficient = 0.033 [95% confidence interval, 0.004 to 0.062]; P = .004) were significant independent predictors for insulin resistance adjusted for diastolic BP, height, BMI, acanthosis nigricans, and high-density lipoprotein cholesterol level.

CONCLUSION

Waist circumference is a predictor of insulin resistance syndrome in children and adolescents and could be included in clinical practice as a simple tool to help identify children at risk.

Islets secretory capacity determines glucose homoeostasis in the face of insulin resistance

BACKGROUND

Debate surrounds the relative importance of impaired beta-cell secretory function versus insulin resistance in type 2 diabetes. We therefore defined insulin secretion and sensitivity in patients with impaired glucose homoeostasis of varying aetiology and duration.

METHODS

126 consecutive patients undergoing an oral glucose tolerance test (OGTT) between 1999 and 2003 were included. Whole-body insulin sensitivity index (ISI) and insulinogenic index derived from the OGTT were determined in 32 healthy controls, 65 type 2 diabetic patients, 15 patients with acromegaly, 10 patients with insulinoma, and 4 patients with HAIRAN syndrome.

RESULTS

Median ISI (quartiles Q25-Q75) of healthy controls and of patients with insulinoma were similar (3.5 [2.8-5.6] and 3.2 [1.7-4.2] respectively) but significantly decreased in patients with acromegaly, type 2 diabetes, and HAIRAN syndrome (2.8 [1.8-3.3], 1.9 [1.4-3], and 0.8 [0.6-1.3] respectively). Despite the decrease in ISI, patients with HAIRAN syndrome and acromegaly maintained normal glucose tolerance by adapting insulin secretion as reflected in the insulinogenic index (106.5 [90.4-127.5] and 49 [24.4-89] in HAIRAN and acromegaly respectively, versus 46.9 [27.3-66.7] in controls). In contrast, type 2 diabetic patients failed to adapt and displayed severely hampered insulin secretion (insulinogenic index of 7.6 [3.8-14.7]). Furthermore, the level of the insulinogenic index correlated significantly with duration of diabetes and HbA1c, which was not the case for the ISI. Insulinoma patients had a decreased insulinogenic index (38.7 [32-83.8]), leading to impaired glucose tolerance despite normal ISI.

CONCLUSIONS

The data are compatible with the notion that beta-cell function rather than insulin sensitivity determines the evolution of hyperglycaemia.

Acanthosis nigricans

Acanthosis nigricans is thickened, velvety, hyperpigmented skin associated with a variety of endocrine disorders, malignancies and medications.

[Obese children with benign acanthosis nigricans and insulin resistance: analysis of 19 cases]

OBJECTIVE

The prevalence of obesity and of type 2 diabetes mellitus in children have increased in the Chinese population over the past two decades, and thus diabetes prevention has become a major concern of public health agencies. Identification of individuals at risk for diabetes is an essential first step in designing and implementing intervention programs. Insulin resistance is the hallmark of the pathophysiology of type 2 diabetes mellitus. Subjects with hyperinsulinemia and impaired glucose tolerance are well accepted as being at high risk for diabetes. Acanthosis nigricans (AN) has been proposed as a reliable marker of hyperinsulinemia, but its utility for predicting hyperinsulinemia has not been systematically evaluated in obese children. In order to further explore the relationship between obese childhood with benign acanthosis nigricans and insulin resistance and type 2 diabetes mellitus, we examined 19 obese children with benign acanthosis nigricans.

METHODS

Nineteen of seventy six obese children (25%) with BMI over 25 enrolled in the Children' Hospital of Zhejiang University School of Medicine fromJune 1st to September 1st in 2003 were studied. Skin biopsies were performed in these 19 obese children with acanthosis nigricans for final diagnosis. Levels of glucose, insulin, and glucose/insulin ratio were measured on fasting blood specimens and anthropometric parameters including waist/hip ratio, fat mass, body fat percentage and body mass index were examined. Oral glucose tolerance tests were also performed in these 19 children with benign acanthosis nigricans.

RESULTS

Anthropometric parameters including waist/hip ratio, fat mass, body fat percentage and body mass index as well as fasting insulin level in acanthosis nigricans group were significantly higher than that of healthy controls (P < 0.01). Fasting glucose to insulin ratio (FGIR) of these 19 obese children with benign acanthosis nigricans was 4.27 +/- 0.53, indicating apparent insulin resistance. One of them was diagnosed as type 2 diabetes mellitus and ten of them showed impaired oral glucose tolerance.

CONCLUSION

Childhood benign acanthosis nigricans is tightly associated with obesity, hyperinsulinemia, insuline resistance and type 2 diabetes mellitus, and may be used as a reliable index of insulin resistance.

Acanthosis nigricans associated with insulin resistance : pathophysiology and management

The association of acanthosis nigricans, skin tags, diabetes mellitus due to insulin resistance, and obesity in adolescents and young adults represents a well defined syndrome. Hyperandrogenism may also be present. The endocrine origin of this condition is beyond doubt. Insulin and insulin-like growth factor-1, and their receptors on keratinocytes are obviously involved in the complex regulations leading to the peculiar epidermal hyperplasia. This condition is unrelated to other types of acanthosis nigricans, including the congenital and the paraneoplastic types. Control of obesity contributes largely to reverse the whole process, essentially by reducing both insulin resistance and compensatory hyperinsulinemia. Several drugs including metformin, octreotide, retinoids and topical colecalciferol (vitamin D(3)) analogs are also beneficial in clearing acanthosis nigricans.

Relation between acanthosis nigricans and insulin sensitivity in overweight Hispanic children at risk for type 2 diabetes

OBJECTIVE

To investigate in a population of Hispanic children if 1) the presence of acanthosis nigricans (AN) is related to insulin sensitivity (S(i)) independent of adiposity and 2) scale scoring AN severity adds to the clinical estimation of insulin sensitivity, above and beyond the presence or absence AN alone.

RESEARCH DESIGN AND METHODS

The study population, 131 Hispanic overweight children (mean BMI percentile 97.0 +/- 3.1, 72 boys, 59 girls, ages 8-13 years, mean Tanner stage 2.4 +/- 1.5) with a family history of type 2 diabetes, underwent a physical examination of the neck to determine AN absence or presence (0-1), AN extent score (0-4 scale), AN texture score (0-3 scale), and an AN combined score (extent + texture; 0-7 scale). S(i) was measured by the frequently sampled intravenous glucose tolerance test and minimal modeling. Multivariate linear regression analysis was used to determine the role of BMI and AN in predicting S(i).

RESULTS

BMI was the main predictor of S(i), explaining approximately 41% of the variance. The presence of AN explained an additional 4% of the variability in S(i); scale scoring of AN extent or texture did not significantly improve the prediction.

CONCLUSIONS

Although AN is an independent risk factor for insulin resistance in overweight Hispanic children at risk for type 2 diabetes, body adiposity is the primary determinant of insulin sensitivity. In addition, scale scoring AN seems of minimal usefulness in clinically estimating the severity of insulin resistance over and above assessing the presence or absence of AN and calculating BMI.

Generalized acanthosis nigricans in an otherwise healthy young child

Acanthosis nigricans in children is usually a benign condition most commonly associated with obesity. Generalized acanthosis nigricans is a very rare condition, especially in childhood. We report a 6-year-old boy with a 4-year history of generalized hyperpigmentation and velvety thickening of the skin. Despite an extensive examination, no evidence for an underlying neoplastic or endocrinologic disease was found.

Microscopic acanthosis nigricans in type 2 diabetes

BACKGROUND

Acanthosis nigricans (AN) has been associated with insulin resistance. Individuals with type 2 diabetes are insulin-resistant and, therefore, could be expected to manifest AN. However, the prevalence and predictors of AN are unknown in this population.

OBJECTIVE

An outpatient population with Type 2 diabetes (DM) was compared with matched controls (C) for microscopic and clinical AN along with measurement of body habitus, insulin, glucose, and androgen levels.

METHODS

Twenty-four individuals with DM (12M, 12F) from a tertiary care center were compared with 24 C (12M, 12F). Fasting glucose, insulin, sex hormone binding globulin, androstenedione, dihydroepiandrosterone sulfate, and testosterone were measured. Height, weight, waist/hip measures, and a clinical survey for acanthosis were recorded. A 2-mm skin biopsy from midaxilla of the nondominant arm was taken for pathological review.

RESULTS

C and DM were matched for age and body mass index (BMI). Prevalence of microscopic AN in C was 12% (3/24) and in DM was 21% (5/24; NS). In C, AN was predicted by waist, waist/hip ratio, and fasting insulin measures, while none of the variables examined was predicative of AN in DM.

CONCLUSIONS

Microscopic acanthosis nigricans was found in similar numbers of people with DM when compared with C. Fasting insulin levels most strongly predicted the presence of AN in C, while no significant predictors of AN were found in the population with DM.

Acanthosis nigricans: a new cutaneous sign in severe atopic dermatitis and Down syndrome

Acanthosis nigricans (AN) occurs associated with many different systemic diseases, such as endocrine disorders and internal malignant neoplasms. To our knowledge, the association of AN with severe atopic dermatitis (AD) or Down syndrome has not been described before. This 82-month retrospective study included 1038 patients: AN was present in 4.9% of atopic patients and 50.9% of subjects with Down syndrome. AN was more frequent in patients with severe AD and in 100% of cases of hand dermatitis and juvenile plantar dermatosis, located on the interphalangeal and metacarpophalangeal joints, whereas in Down syndrome other flexures were also affected. The pathogenesis of AN in AD is unknown, but in Down syndrome it seems to be related to obesity. Possible insulin resistance underlyng the pathogenesis of AN in these patients is still unknown.

HAIR-AN syndrome: a multisystem challenge

HAIR-AN syndrome is an acronym for an unusual multisystem disorder in women that consists of hyperandrogenism (HA), insulin resistance (IR) and acanthosis nigricans (AN). The precipitating abnormality is thought to be insulin resistance, with a secondary increase in insulin levels and subsequent overproduction of androgens in the ovaries. Long periods of hyperinsulinism and, some suspect, hyperandrogenism can result in the cutaneous manifestation of acanthosis nigricans. Patients are often concerned about the physical manifestations of this disorder, including virilization and acanthosis nigricans, and may be less aware of systemic problems. Physicians should assess women with these problems for an underlying endocrine abnormality. Although a treatment regimen for the HAIR-AN syndrome has not been established, antiandrogen therapy and weight loss are useful.

Highly activated Fgfr3 with the K644M mutation causes prolonged survival in severe dwarf mice

Several gain-of-function mutations in a receptor tyrosine kinase, fibroblast growth factor receptor 3 (FGFR3), cause dwarfism in humans. Two particularly severe dwarfisms, thanatophoric dysplasia type II (TDII) and severe achondroplasia with developmental delay and acanthosis nigricans (SADDAN), are associated with glutamic acid (E) and methionine (M) substitutions at the K650 residue in the kinase domain. TDII is lethal at birth, whereas most of the SADDAN patients survive the perinatal period. However, FGFR3 with the SADDAN mutation is more activated than FGFR3 with the TDII mutation in vitro. To find out whether the K650M mutation also causes the SADDAN phenotype, we introduced the corresponding point mutation (K644M) into the mouse Fgfr3 gene. Heterozygous mutant mice show a phenotype similar to human SADDAN, e.g. the majority of the SADDAN mice survive the perinatal period. This suggests that the survival of SADDAN patients is indeed attributed to the K650M mutation in FGFR3. The long bone abnormalities in SADDAN mice are milder than the TDII model. In addition, overgrowth of the cartilaginous tissues is observed in the rib cartilage, trachea and nasal septum. The FGF ligand at the low concentration differentially activates Map kinase in primary chondrocyte cultures from wild-type and SADDAN mice. Comparisons of the molecular bases of the phenotypic differences in SADDAN and TDII mice may increase our understanding of the factors that influence the severity in these two related skeletal dysplasias.

Alstrom syndrome with hepatic dysfunction: report of one case

Alstrom syndrome is a rare autosomal recessive disorder associated with early childhood retinopathy, progressive sensorineural hearing loss, truncal obesity, and acanthosis nigricans. We report a 10-year-old boy with Alstrom syndrome presenting with general malaise and abnormal liver function for 1 year. In addition to the above mentioned features, he also had hyperglycemia and hyperinsulinemia. The mechanism responsible for the persistent elevation of liver enzymes could not be identified. To the best of our knowledge, this is the first-reported case of Alstrom syndrome with hepatic dysfunction in Taiwan.

A quantitative scale of acanthosis nigricans

OBJECTIVE

To develop and validate a scale for acanthosis nigricans (AN).

RESEARCH DESIGN AND METHODS

Subjects were participants from the San Antonio Family Diabetes Study and the San Antonio Family Heart Study. A total of 406 subjects were independently examined for AN by at least two observers. Five locations were examined: the neck, axilla, elbows, knuckles, and knees. Interobserver concordance and kappa statistics were calculated to determine replicability of the scale. Comparisons of diabetes-related risk factors by AN score were also calculated.

RESULTS

Only the neck had consistently high kappa statistics, and thus, other locations were excluded from further analyses. Elevated AN was strongly associated with elevated fasting insulin and BMI in both diabetic and nondiabetic subjects. Elevated AN was also strongly associated with elevated fasting glucose, systolic blood pressure, and diastolic blood pressure, and with decreased HDL in nondiabetic subjects. In diabetic subjects, elevated AN was associated with elevated total cholesterol.

CONCLUSIONS

We have developed a scale for AN that is easy to use, has high interobserver reliability in Mexican Americans, and correlates well with fasting insulin and BMI. This scale will permit longitudinal and cross-sectional evaluation of AN and will permit the evaluation of AN as a trait in genetic studies.

Pregnancy after treatment with the insulin-sensitizing agent troglitazone in an obese woman with the hyperandrogenic, insulin-resistant acanthosis nigricans syndrome

OBJECTIVE

To report a case of unassisted pregnancy after 5 months of troglitazone treatment in a severely hyperandrogenic, insulin-resistant woman with acanthosis nigricans (HAIR-AN) previously managed with depot leuprolide acetate (LA) plus oral contraceptive and dexamethasone therapy.

DESIGN

Case report.

SETTING

Private infertility clinic.

PATIENT(S)

A 28-year-old African-American woman with excessive obesity (body mass index = 42 kg/m2) and HAIR-AN syndrome.

INTERVENTION(S)

Androgen suppression with depot LA plus oral contraceptive and dexamethasone therapy, troglitazone treatment resulting in normalization of fasting insulin and testosterone, spontaneous menses, and an unassisted pregnancy.

MAIN OUTCOME MEASURE(S)

Luteinizing hormone and testosterone concentrations, fasting insulin and glucose levels, insulin-glucose ratios, hCG levels, and ultrasound examinations.

RESULT(S)

Spontaneous menses followed by an intrauterine pregnancy after 5 months of treatment with troglitazone, an insulin-sensitizing agent, in a woman with severe HAIR-AN syndrome whose hyperandrogenism previously could be normalized only with depot LA plus oral contraceptive therapy and dexamethasone.

CONCLUSION(S)

Troglitazone treatment resulted in attenuation of both hyperinsulinemia and hyperandrogenism in an obese woman with HAIR-AN and resulted in resumption of menses and a spontaneous pregnancy.

Costello syndrome: phenotype, natural history, differential diagnosis, and possible cause

We describe 8 patients affected with Costello syndrome including an affected sib pair and review the literature on 29 previously reported cases. We emphasize an association with advanced parental age, which is consistent with autosomal dominant inheritance with germline mosaicism. The pathogenesis appears to involve metabolic dysfunction, with growth disturbance, storage disorder appearance, acanthosis nigricans, hypertrophic cardiomyopathy, and occasional abnormalities of glucose metabolism. Although the cause is currently unknown, Costello syndrome is interesting because of a potential genetic-metabolic etiology.

Genealogy, natural history, and phenotype of Alström syndrome in a large Acadian kindred and three additional families

We describe a large Acadian kindred including 8 Alstrom Syndrome (AS) patients, with an age range of 4 to 26 at the time of clinical assessment. The affected subjects come from 5 nuclear families within this kindred. The phenotype includes early childhood retinopathy, progressive sensorineural hearing loss, truncal obesity, and acanthosis nigricans. In addition, hyperinsulinemia and hypertriglyceridemia with normal cholesterol levels were observed in most affected individuals tested. Non-insulin dependent diabetes mellitus and growth retardation appear to be age-related manifestations that occur post-adolescence. Younger affected children are not overtly hyperglycemic and are normal or above average height for age. Although the AS patients in kindred 1 presumably carry the same mutation, many manifestations of the disease are variable. For example, of the 8 children in the Acadian kindred, 4 have scoliosis, 2 have had infantile cardiomyopathy, 2 are hypothyroid, 1 has had hepatic dysfunction and is hypertensive, and 4 have developed asthma. Seven subjects described in this kindred exhibit developmental delay. One additional manifestation not described widely in the literature, advanced bone age, was observed in all subjects tested. The clinical data from this large Acadian kindred, together with information obtained from 4 additional AS patients in 3 unrelated kindreds, confirm and extend clinical observations previously described. In addition, the Acadian kindred with multiple affected individuals, probably arising from a common founder, should allow for identification of the chromosomal localization of a gene causing AS.

Terra firma-forme dermatosis

Terra firma-forme dermatosis (TFFD) is a relatively common but usually unrecognized clinical problem. The cause is unknown. The changes usually occur on the neck in childhood as dirty brown patches that cannot be removed with soap but are easily removed with alcohol. Terra firma-forme dermatosis may be mistaken for acanthosis nigricans.

Long-term octreotide treatment reduced hyperinsulinemia, excess body weight and skin lesions in severe obesity with acanthosis nigricans

A boy affected by severe obesity (kg 117, Body Mass Index 37 kg/m2) and acanthosis nigricans, was treated with octreotide for 150 days (50 micrograms x three daily subcutaneous administrations). Before treatment the patient showed an exaggerated insulin (IRI) and C-peptide (CPR) response to a standard meal with a lowering in after-meal CPR/IRI molar ratio. During octreotide treatment both IRI and CPR response was reduced but CPR/IRI molar ratio rised after meal indicating an increase in hepatic insulin removal. Body weight and acanthosis nigricans were sharply reduced during treatment and the reduction was still maintained six months after the cessation of therapy. Furthermore, IRI and CPR response, as well as the behaviour of CPR/IRI molar ratio, remained within normal range. In conclusion long-term octreotide treatment has been able to correct hyperinsulinemia and to reduce body weight and acanthosis nigricans.

Hyperandrogenism, insulin resistance, and acanthosis nigricans (HAIR-AN) syndrome: spontaneous remission in a 15-year-old girl

Acanthosis nigricans is associated with many diseases, including internal malignancies, genetic disorders, and endocrine abnormalities. Insulin resistance frequently accompanies endocrine-associated acanthosis nigricans. We describe a patient with acanthosis nigricans associated with hyperandrogenism and extreme insulin resistance that spontaneously resolved after a marked decrease in insulin receptor antibodies.

Crouzon disease with acanthosis nigricans and melanocytic nevi

A number of craniofacial malformation syndromes are characterized by prominent abnormalities of the skin, hair, nails, and mucous membranes. Crouzon disease has been reported in association with severe acanthosis nigricans in 12 patients. We report a new case of this association in a 16-year-old woman with multiple melanocytic nevi. Melanocytic nevi have been already reported in the medical literature in association with several congenital syndromes, although, to our knowledge, not with Crouzon disease.

Acanthosis nigricans: a marker for hyperinsulinemia

A 12-year-old girl developed acanthosis nigricans due to increased levels of serum insulin. Hyperinsulinemia has been recognized as the underlying cause in most cases of acanthosis nigricans. In this paper we outline a typical clinical case with special regard to the proposed pathogenesis.

Insulin resistance in a patient with ovarian stromal hyperthecosis and the hyperandrogenism, insulin resistance and acanthosis nigricans syndrome. Report of a case with a possible endogenous ovarian factor

Insulin resistance is a common feature of ovarian stromal hyperthecosis and is usually accompanied by hyperandrogenemia. A patient had ovarian stromal hyperthecosis, and her hyperandrogenemia resolved, possibly due to the development of a type of ovarian fibrosis similar to so-called ovarian fibromatosis, without a concomitant improvement in her insulin resistance. The insulin resistance improved markedly, however, after bilateral oophorectomy.

Decreased insulin sensitivity in prepubertal girls with premature adrenarche and acanthosis nigricans

Benign premature adrenarche (PA) is the term used to refer to girls with the early development of pubic hair before the age of 8 yr and is characterized by mild hyperandrogenism. Hyperandrogenism in adult women is often not as benign and has been associated with insulin resistance, acanthosis nigricans (AN), and the polycystic ovary syndrome. We have seen a group of young girls with PA who have also been found to have AN. The purpose of this study was to determine whether there are any clinical and biochemical differences in those girls with PA with and without AN. Twelve girls with PA were divided into two groups at the time of evaluation: group I, those without AN (n = 5); and group II, those with AN (n = 7). Adrenal androgen levels were determined in all subjects by a 60-min ACTH stimulation test. Insulin sensitivity was measured by the frequently sampled iv glucose tolerance test with tolbutamide and was assessed using the modified minimal model. Mean chronological age, bone age, and weight for length index were similar in the two groups. The baseline and stimulated levels of adrenal androgens were also not significantly different between the two groups. The group I girls (without AN) had an insulin sensitivity index of 6.75 +/- 1.31, which was in the normal prepubertal range. This was significantly different from that in group II (with AN), who had an insulin sensitivity index of 3.69 +/- 1.29. Therefore, many girls with premature adrenarche can have AN and decreased insulin sensitivity. Whether these girls have a truly benign course or are at risk of ovarian dysfunction or carbohydrate intolerance needs to be assessed.

Case report: defective beta and alpha cell regulation in patients with hyperinsulinemia and acanthosis nigricans

Beta cell hypersecretion is associated with the syndrome of hyperandrogenism, insulin resistance, and acanthosis nigricans. It is unknown whether concomitant alpha cell secretory dysfunction occurs in patients with this syndrome. The authors evaluated the gastroenteropancreatic hormones in four family members with varying degrees of the hyperandrogenism, insulin resistance, and acanthosis nigricans syndrome. Gastroenteropancreatic hormones were measured during oral glucose tolerance test with and without subcutaneous octreotide injection. The study revealed that the administration of subcutaneous octreotide resulted in suppression of beta cell function (insulin and c-peptide) but had no effect or a delayed effect on alpha cell secretion (glucagon). Furthermore, the severity of glucagon abnormalities paralleled that of beta cell hypersecretion and the clinical and phenotypic manifestations of acanthosis nigricans in our four patients. We speculate that this alpha cell aberration could potentially be involved in the altered glucose homeostasis and perhaps the skin manifestations of this syndrome. Therefore, glucagon levels should be evaluated in the hormonal studies in patients with hyperandrogenism, insulin resistance, and acanthosis nigricans syndrome.

Hyperandrogenism, insulin resistance and acanthosis nigricans. 10 years of progress

Polycystic ovary disease is a heterogeneous endocrinopathy with many interacting causal factors. One potential such factor is chronic hyperinsulinemia. Multiple, independent lines of evidence support the contention that chronic hyperinsulinemia causes ovarian hyperandrogenism. This evidence includes: (1) mutations in the insulin receptor gene that cause severe hyperinsulinemia appear to be associated with ovarian hyperandrogenism, (2) insulin stimulates ovarian thecal and stromal androgen secretion in vitro, and (3) in some experimental models, manipulation of circulating insulin concentrations results in changes in circulating androgens. Although the association between hyperinsulinemia and hyperandrogenism remains to be fully explained at the molecular level, chronic hyperinsulinemia appears to be an important cause of hyperandrogenism.

The hyperandrogenic-insulin-resistant acanthosis nigricans syndrome: therapeutic response

The hyperandrogenic-insulin-resistant acanthosis nigricans syndrome affects between 2% and 5% of hirsute women and is characterized by INS resistance, elevated INS levels, acanthosis nigricans, and androgen excess. These patients' response to therapy is unclear, although long-acting GnRH-a suppression has been proposed. The objective of this study was to determine the success of OC in suppressing the hyperandrogenemia of five patients with the hyperandrogenic-insulin-resistant acanthosis nigricans syndrome and the subsequent response to GnRH-a suppression of those women failing initial therapy. After 6 months of OC and SPA therapy, four patients experienced adequate suppression of free T, an increase in SHBG levels, and a subjective improvement in hair growth rate. Two also reported an improvement in hair texture. The total and free T levels in the fifth patient did not suppress after 8 months of OC therapy. Nevertheless, in this patient the administration of a GnRH-a along with hormonal replacement and SPA adequately suppressed free and total T, increased SHBG, and dramatically decreased the shaving interval. In conclusion, although GnRH-a suppression and hormonal replacement can be helpful in patients not responding to standard therapy, the majority of patients with the hyperandrogenic-insulin-resistant acanthosis nigricans syndrome will respond favorably to OC treatment. It is also clear that although hyperinsulinemia augments LH-stimulated androgen biosynthesis in vivo, it does not appear to be able to initiate or maintain androgen production in the absence of adequate gonadotropin stimulation.

Acanthosis nigricans--decreased extracellular matrix viscosity: cancer, obesity, diabetes, corticosteroids, somatotrophin

Acanthosis nigricans is a reaction pattern to over a dozen different causes. The skin, most classic in the axilla, is dark, soft, velvet-like with fine folding and papillae. The mechanism of this skin change is decreased viscosity of extracellular matrix (ECM) combined with mechanical extrusion of ECM into papillae extending out from the upper dermis. It occurs in obesity (increased mechanical pressure on ECM), diabetes (decreased quality of glycosaminoglycans) (GAG), excess corticosteroids (decreased quality of GAG), pineal tumors (increased ECM and edema), other endocrine disorders (alterations in the quality of GAG), multiple genetic variants (structural and chemical change), from drugs such as nicotinic acid, estrogens, corticosteroids (weakened or altered GAG) and adenocarcinoma (fractions of depolymerized or altered GAG released from the tumor area are incorporated into and weaken the skin GAG). Acanthosis nigricans was first reported in 1890 as a cutaneous sign of internal malignancy. Acanthosis nigricans presents an opportunity to better understand what is occurring in the ECM in many disorders. The understanding of the association of AN and internal malignancy will expand our understanding of how a neoplasm decreases generalized ECM viscosity.

Vulvar acanthosis nigricans: a marker for insulin resistance in hirsute women

OBJECTIVE

To determine the frequency of acanthosis nigricans (AN) in a group of hirsute, hyperandrogenic women and to determine the body site most frequently affected.

DESIGN

Cross-sectional observational study.

SETTING

University teaching hospital.

PATIENTS, PARTICIPANTS

Reproductive age, nonhypertensive, nondiabetic women referred for evaluation of hirsutism, documented to have hyperandrogenism, without medications known to influence lipid, carbohydrate, or hormonal metabolism.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Presence of AN. 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.

RESULTS

Twenty-four of 43 women were found to have AN. Although AN was identified at several body sites including the axilla (n = 14), on the nape of the neck (n = 13), below the breasts (n = 7), and on the inner thigh (n = 7), it was always present on the vulva in women who displayed one or more lesions. Acanthosis nigricans was found only in the obese, hirsute, hyperandrogenic women. These women were the most insulin resistant.

CONCLUSIONS

Acanthosis nigricans and insulin resistance are found frequently in obese, hirsute, hyperandrogenic women. The vulva is the most likely place to find this marker.

[Amenorrhea, insulin resistance and acanthosis nigricans. A hyperandrogenic and a normoandrogenic clinical forms]

Two cases of HAIR-AN syndrome (hyperandrogenism, insulin resistance and acanthosis nigricans) are presented. The first case corresponds to a female with a systemic lupus erythematosus and acanthosis nigricans in which an insulin resistance was documented; the patient was in amenorrhea with severe hypoestrogenism, although she did not have clinical signs of hyperandrogenism and serum androgen levels were normal. This case corresponds to a HAIR-AN syndrome associated to autoimmune diseases or type A of Kahn. The second case is a young female with clinical signs of hyperandrogenism associated to high testosterone levels; she had acanthosis nigricans and fasting and postprandial hyperinsulinemia. Probably, this case corresponds to a type A or C HAIR-AN syndrome in which there is a decrease in the number of insulin receptors or a post receptor defect in insulin action.

Excess insulin binding to insulin-like growth factor receptors: proposed mechanism for acanthosis nigricans

Clinical and epidemiologic evidence has shown acanthosis nigricans to be closely related to defective tissue utilization of insulin in a number of previously recognized (e.g., obesity, lipodystrophy, and leprechaunism) as well as recently characterized (e.g., type A and type B syndromes) disorders. This article reviews the relationship of acanthosis nigricans to these insulin-resistant states. It also focuses attention on the possibility that interaction between excessive amounts of circulating insulin with insulin-like growth factor receptors on keratinocytes and dermal fibroblasts leads to the development of acanthosis nigricans.

Organic mood disorder associated with the HAIR-AN syndrome

The HAIR-AN syndrome is characterized by hyperandrogenism, insulin resistance, and acanthosis nigricans. The authors report the first case of an organic mood disorder associated with this condition that improved markedly in response to ovarian suppression with oral contraceptives. The proposed pathophysiology of this syndrome is also discussed.

Insulin effects on glucose and potassium metabolism in vivo: evidence for selective insulin resistance in humans

The effects of insulin on in vivo glucose use and potassium uptake in healthy humans are well documented. However, the interrelationship between these two processes is not fully defined. In order to characterize it, we have used the euglycemic clamp technique on six normal volunteers, two patients with acanthosis nigricans and insulin resistance (AN), and one patient with idiopathic nonazotemic hyperkalemia (HK). In the basal state, all patients had normal fasting blood sugar, the AN patients had fasting hyperinsulinemia (600% of controls), and the HK patient had an elevated plasma potassium level of 5.1 mmol/L (n = 4.2 +/- 0.2 mmol/L). During low dose (1 mU/kg.min), and high dose (10 mU/kg.min) insulin infusions, normals used glucose at a rate of 220 +/- 10 and 470 +/- 20 mg/M2.min, respectively. The HK patient had a normal glucose use at both infusion rates, but the AN patients had a 20% decrease of glucose use compared to normals at the two infusion rates. In normal patients, plasma potassium fell by 0.7 and 1.4 mmol/L at the end of the two infusion periods, respectively. AN patients had a similar fall in potassium, but the HK patient displayed no change in plasma potassium levels during a low dose insulin infusion, and only a 0.6 mmol/L drop during the high dose insulin infusion. These results indicate that: 1) patients with AN are resistant to insulin action on glucose use, 2) AN patients have a normal response to insulin on potassium uptake, 3) HK is a patient with normal response to insulin on glucose use, and 4) this patient is resistant to insulin action on potassium uptake.

IN CONCLUSION

1) we have demonstrated the independence of insulin action on glucose and potassium uptake in vivo, 2) we documented the existence of selective insulin resistance in the above patients, 3) we speculate, that in patients with a normal response to insulin on one parameter of its actions, and subnormal response on another parameter, a postreceptor defect rather than a receptor abnormality must exist.

Use of in vitro clonogenic assays to differentiate acquired from genetic causes of insulin resistance

Insulin resistance may be due directly to genetically programmed disorders of insulin action or acquired defects in which environmental factors influence insulin action. To address the issue of this distinction, we studied the ability of insulin to stimulate colony formation in primary cultures of erythroid progenitors (assumed to retain environmental influences) and immortalized T lymphocytes (presumed to reflect only genetic influences). Four patients with hyperinsulinemia and disturbed glucose metabolism were studied (2 patients with acanthosis nigricans, 1 of whom had circulating anti-insulin-receptor antibodies, 1 with partial lipodystrophy, and 1 with Cushing's syndrome). The mean colony-forming ability of their erythroid progenitor cells in response to insulin stimulation (less than or equal to 1.6 pM) was significantly blunted compared with control cells (P less than 0.05). The mean responsiveness of their immortalized T-lymphoblast cell lines to similar insulin concentrations was no different than that of control T-lymphocyte lines, consistent with an acquired cause for the observed insulin resistance in each case. A T-lymphocyte line from a patient with leprechaunism, however, showed no stimulation in response to physiological concentrations of insulin. With these same in vitro methodologies, there was normal T-lymphocyte line responsiveness to insulinlike growth factor I (IGF-I) or insulin concentrations greater than 8.6 pM; both of these responses could be completely blocked by preincubation with an antibody to the IGF-I receptor. These findings suggest that, despite resistance to physiological levels of insulin, the high circulating insulin concentrations present in the serum of these patients could mediate unwanted tissue-specific growth through an intact IGF-I receptor-effector mechanism.

[Inhibition of pancreatic beta-cell secretion during a "glucose-clamp" in subjects with acanthosis nigricans]

It has long been known that acanthosis nigricans is accompanied by insulin resistance. In certain insulin-resistant states, including obesity, a more sluggish response to the insulin/insulin inhibition feedback normally present in pancreatic beta cells has been documented. Some have claimed a sort of beta-cell insulin resistance "parallel" to that of the peripheral tissues. The present study assesses the efficiency of the insulin/insulin feedback in acanthosis nigricans patients, measuring the inhibition of the production of C-peptide (the indicator of beta cell secretion) induced by the administration of exogenous insulin during glucose clamping. This was done in order to compare the roles of the peripheral tissues and the beta cells in producing the insulin resistance typical of acanthosis nigricans. The study using the glucose-insulin clamp technique was conducted on 4 Acanthosis Nigricans patients with normal glucose tolerance and 4 healthy controls, the drop in C-peptide levels after the administration of exogenous insulin being assessed in the course of both steady states. The results showed that the acanthosis nigricans patients retained a beta cell response to the exogenous insulin through their peripheral tissues presented a reduced sensitivity to insulin as revealed by the glucose-insulin clamp. It therefore seems reasonable to attribute the endocrine metabolic alteration found in Acanthosis Nigricans to a peripheral receptor and/or post receptor alteration rather than central alterations in the beta cells that have yet to be demonstrated. It is concluded that in acanthosis nigricans the peripheral insulin resistance is primarily independent phenomenon and not "parallel" to insulin/insulin feedback.

Role of obesity and hyperinsulinemia in the insulin resistance of obese subjects with the clinical triad of polycystic ovaries, hirsutism and acanthosis nigricans

The insulin resistance of 4 nonobese and 8 obese patients with polycystic ovaries, hirsutism and benign acanthosis nigricans, and of 6 'obese normal' apart from obesity and 10 normal female subjects was evaluated by means of an intravenous insulin tolerance test and by measuring basal and insulin responses to an oral glucose load. The patients with polycystic ovaries, hirsutism and acanthosis had a decreased hypoglycemic response to exogenous insulin. The subjects with polycystic ovaries presented a significantly greater mean glucose response area for the same or greater mean insulin response area than the obese or nonobese normal subjects. The insulin resistance in the patient with polycystic ovaries, hirsutism and acanthosis nigricans could not be exclusively ascribed to a reduced receptor number, but also appeared to be due to a simultaneous postbinding defect probably related to the high insulin levels in patients with polycystic ovaries be they obese or not. The elevated plasma androgens and the presence of acanthosis found in these patients are likely also related to the hyperinsulinemia. To evaluate the influence of obesity, obese and nonobese patients with acanthosis nigricans and polycystic ovaries were compared. Higher insulin levels were found in the thin subjects, which could explain their greater insulin resistance and more severe hyperandrogenism. The comparison between obese patients with and those without acanthosis nigricans and polycystic ovaries suggested that, despite similar insulin levels, the greater known duration of obesity (probably also of the hyperinsulinemia) of the former was a possible explanation for their more intense insulin resistance and higher testosterone levels.