Sex Differences in Keloidogenesis: An Analysis of 1659 Keloid Patients in Japan

INTRODUCTION: Keloids are a cutaneous fibroproliferative disorder. Despite the fact that keloids are relatively common lesions, the statistics of patient with keloids especially sex difference remain unknown. To better understand it, we conducted an extensive cross-sectional analysis of a large cohort of patients with keloids (n = 1659). The study showed for the first time that female sex may be an inherent keloid risk factor. METHODS: This cross-sectional study of 1659 consecutive patients with keloids who attended a plastic surgery outpatient clinic in Japan in 2014 analyzed age at keloid onset, age at the first medical examination for keloid, and the influence of sex on these variables. RESULTS: In both male and female patients, the keloids were most likely to start in puberty and there was no significant difference in the mode value for age of onset (16 vs. 20 years). Though female patients were twice as prevalent as male patients at nearly all onset ages, female patients predominated over male patients with a gender ratio of 2.7:1 in cases of onset before the age of 15 years. Moreover male and female patients did not differ in terms of the mean ± SD duration between keloid onset and the first medical examination. This finding shows that female patients do not get their keloids examined earlier than male patients. These observations together suggest that female sex may promote early keloid development due to physiological, not social, reasons. CONCLUSION: This is the first report to suggest that female sex may drive keloidogenesis because of physiological reasons. Individuals were most likely to seek a medical examination almost 10 years after onset, regardless of sex. These findings provide new insight into the importance of sex in the development and progression of keloids. Future studies should address the influence of sex hormones on the keloid.