['Pathophysiological mechanisms leading to chordee in patients with hypospadias and to the hidden state of buried penis in the prepubic fat remain unclear. Resection of dartos tissue usually makes the penis straight in patients with hypospadias and corrects it in those with buried penis, suggesting a common pathophysiology related to dartos tissue.', 'Tissue samples from 113 children undergoing primary penile surgery for hypospadias (94 patients), epispadias (1) or buried penis (18) were collected between November 2011 and September 2013. Tissue samples from 79 children undergoing circumcision for nonmedical reasons served as controls. All samples were stained with smooth muscle actin and analyzed by the same pathologist, who was blinded to indication for surgery. Chi-square and Fisher exact tests were applied.', 'Three different dartos tissue patterns were observed. Pattern I (normal) consisted of smooth muscle fibers of dartos tissue organized in a parallel configuration in the subcutaneous tissue. Pattern II was characterized by poorly developed and hypotrophic smooth muscle fibers. Pattern III was determined by randomly distributed smooth muscle fibers in the subcutaneous tissue, without parallel configuration. Pattern I was observed in 45 circumcision specimens (64%). Of buried penis cases 78% were considered abnormal (pattern II in 4 cases and III in 10, p = 0.001). Of hypospadias cases 70% were considered abnormal (pattern II in 31 cases, III in 32, and mixed II and III in 3, p < 0.001). The only epispadias case was designated pattern II.'] Is congenital penile pathology associated with abnormal development of the dartos muscle : a prospective study of primary penile surgery at a tertiary referral center?