Congenital Prepubic Sinus as a Variant of Incomplete Urethral Dorsal Duplication: A Case Report with New Insights into its Immunohistochemical Characterization and a Comprehensive Literature Review.

Congenital prepubic sinus (PS) is an extremely infrequent malformation consisting of a prepubic fistulous tract that classically does not communicate with the genitourinary system. Previous studies centered on its immunohistochemical characterization have shown inconsistent results, and the etiology has not been clarified. We present the case of a 2-year-old male who presented since birth with a fistulous orifice on the dorsum of the penis. He had no associated symptoms. Under general anesthesia, the fistulous tract was explored, and methylene blue was instilled through it. After cystoscopically verifying the absence of communication with the urethra, a complete resection of the lesion was performed. The immunohistochemical study showed positivity for low and high molecular weight keratins and a transitional pattern for keratin 7 and GATA3, with positivity at cul de sac level and negativity at proximal level. These findings suggest that this lesion is an incomplete dorsal duplication variant.