Correspondence Acne keloidalis nuchae in Latin America: is there a different phenotype? To the editor: We read with great interest the article entitled “Acne Keloida- lis Nuchae: Risk Factors and Associated Disorders – A Retro- spective Study” by East-Innis A et al. 1 In this noteworthy paper, the authors recorded demographic and clinical data of patients with acne keloidalis nuchae (AKN) to identify cutaneous and extracutaneous disorders that might be associated with an increased risk of developing metabolic syndrome. They con- cluded that AKN may be associated with metabolic syndrome. We have previously highlighted a similar association in a ser- ies of cases in mestizo women with AKN. 2 Our patients had an average body mass index of 31.4, insulin levels of about 25 mU/ml and a homeostatic model assessment (HOMA) index ≥4.30, which are findings consistent with insulin resistance (IR). However, the scenario described is not the most common since AKN has been recognized in medical literature as being, almost exclusively, a disease of young African descendants. 3 Recently, in our center, we have diagnosed 36 patients with AKN. We have found similar results to the East-Innis et al. study. In our sample, the average age was 29, close to that seen in the East-Innis et al. study (25 years old). Moreover, in our population, only 11% were female, resulting in a male to female ratio of approximately 8 : 1, a distribution that proved to be statistically significant (P = 0.000). This distribution was also appreciated in the East-Innis et al. study, where 12% were females, leading to a male to female ratio of 7 : 1. Furthermore, the population studied by East Innis et al. was of African des- cent, while 78% of our patients were not African descendants. 1 In addition, we found that 61% of our patients presented with metabolic syndrome (MS) in accordance with the criteria of the International Diabetes Federation. 4 This proportion differs with the one reported in the East-Innis et al. study, where 34.9% of patients presented metabolic syndrome. 1 Nevertheless, we do not know which criteria were applied in this publication to assess such diagnosis. The higher rate of MS in our cases could be attributed to the distinct ethnicity or even physical traits such as type of hair. We do not know if there is an association between such factors and MS. East-Innis et al. suggested that further studies should explore whether IR plays a role in the causation of AKN or not. However, the proportion of patients with IR was not reported. Also, only a single patient presented with acanthosis nigricans. 1 Conversely, we found that 75% of our patients had insulin resistance (P = 0.004) and 81% acan- thosis nigricans (P = 0.001). Nowadays, it is known that diabetic neuropathy debuts as soon as MS onsets, presenting with its characteristic signs and symptoms, of which pruritus is well described. 5 At the same time, pruritus is the most frequent symptom in AKN (71%) which could favor the development of chronic folliculitis. 6 There are numerous inflammatory dermatoses such as psoriasis that appear in the context of MS, and it would not be surprising that chronic folliculitis of AKN could be another one. Chronic folliculi- tis might mimic the pathogenesis of any scarring alopecia (including AKN), where loss or inflammation of the sebaceous glands ensues followed by their destruction. 7 Since sebum secretion may be an important elimination route for either excessive circulating lipids, such as cholesterol and triglyc- erides, or fat-soluble substances, their destruction could lead their accumulation in the serum and produce the characteristic elements that present in MS. 7,8 Further studies are needed to understand the role of MS, acanthosis nigricans, and IR itself in the pathogenesis of AKN, and confirm if Latin Americans who are not African descendants represent a phenotype to be differentiated from the prototypical AKN patient. Acknowledgments I. Cherrez Ojeda is a candidate at the Doctorate Program of Biomedical Research and Public Health, Universitat Autonoma de Barcelona, Barcelona, Spain. Enrique Loayza 1,2, *, MD, MsC Emanuel Vanegas 3,4 , MD Annia Cherrez 5,4 , MD Ivan Cherrez Ojeda 3,4 , MD, MsC, PhDc 1 School of Medicine, Universidad de Guayaquil, Guayaquil, Ecuador 2 Department of Dermatology, Hospital Luis Vernaza, Guayaquil, Ecuador 3 School of Medicine, Universidad Especialidades Esp  ıritu Santo, Samborond on, Ecuador 4 Respiralab, Respiralab Research Group, Guayaquil, Ecuador 5 Department of Dermatology and Venereology, University Medicine Rostock, Rostock, Germany *E–mail: drloayza@hotmail.com Funding: No support from any organization for the submitted work has been provided. ª 2017 The International Society of Dermatology International Journal of Dermatology 2017 1